prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  CentOS 6 image doesn't build with clingo on Dockerhub
  ### Steps to reproduce
  
  Has to do with failure on centos:6
  
  ```
  Step 17/19 : RUN spack spec hdf5+mpi
   ---> Running in 8335d48ff53f
  ==> Warning: Spack will not check SSL certificates. You need to update your Python to enable certificate verification.
  ==> Warning: Spack will not check SSL certificates. You need to update your Python to enable certificate verification.
  ==> Warning: the original concretizer is currently being used.
          Upgrade to "clingo" at your earliest convenience. The original concretizer will be removed from Spack starting at v0.18.0
  ==> Error: cannot bootstrap the "clingo" Python module from spec "clingo-bootstrap@spack+python %gcc target=x86_64"
  Input spec
  --------------------------------
  hdf5+mpi
  
  Concretized
  --------------------------------
  ==> Bootstrapping clingo from pre-built binaries
  The command 'docker-shell spack spec hdf5+mpi' returned a non-zero code: 3
  ```
  
  ---
  
  So it bootstraps *during* concretization?
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `lib/spack/spack/schema/container.py`
  Content:
  ```
  1 # Copyright 2013-2021 Lawrence Livermore National Security, LLC and other
  2 # Spack Project Developers. See the top-level COPYRIGHT file for details.
  3 #
  4 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
  5 """Schema for the 'container' subsection of Spack environments."""
  6 
  7 _stages_from_dockerhub = {
  8     'type': 'object',
  9     'additionalProperties': False,
  10     'properties': {
  11         'os': {
  12             'type': 'string',
  13             'enum': ['ubuntu:18.04',
  14                      'ubuntu:16.04',
  15                      'centos:7',
  16                      'centos:6']
  17         },
  18         'spack': {
  19             'type': 'string',
  20         },
  21     },
  22     'required': ['os', 'spack']
  23 }
  24 
  25 _custom_stages = {
  26     'type': 'object',
  27     'additionalProperties': False,
  28     'properties': {
  29         'build': {'type': 'string'},
  30         'final': {'type': 'string'}
  31     },
  32     'required': ['build', 'final']
  33 }
  34 
  35 #: List of packages for the schema below
  36 _list_of_packages = {
  37     'type': 'array',
  38     'items': {
  39         'type': 'string'
  40     }
  41 }
  42 
  43 #: Schema for the container attribute included in Spack environments
  44 container_schema = {
  45     'type': 'object',
  46     'additionalProperties': False,
  47     'properties': {
  48         # The recipe formats that are currently supported by the command
  49         'format': {
  50             'type': 'string',
  51             'enum': ['docker', 'singularity']
  52         },
  53         # Describes the base image to start from and the version
  54         # of Spack to be used
  55         'images': {'anyOf': [_stages_from_dockerhub, _custom_stages]},
  56         # Whether or not to strip installed binaries
  57         'strip': {
  58             'type': 'boolean',
  59             'default': True
  60         },
  61         # Additional system packages that are needed at runtime
  62         'os_packages': {
  63             'type': 'object',
  64             'properties': {
  65                 'command': {'type': 'string', 'enum': ['apt', 'yum']},
  66                 'update': {'type': 'boolean'},
  67                 'build': _list_of_packages,
  68                 'final': _list_of_packages
  69             },
  70             'additionalProperties': False
  71         },
  72         # Add labels to the image
  73         'labels': {
  74             'type': 'object',
  75         },
  76         # Add a custom extra section at the bottom of a stage
  77         'extra_instructions': {
  78             'type': 'object',
  79             'additionalProperties': False,
  80             'properties': {
  81                 'build': {'type': 'string'},
  82                 'final': {'type': 'string'}
  83             }
  84         },
  85         # Reserved for properties that are specific to each format
  86         'singularity': {
  87             'type': 'object',
  88             'additionalProperties': False,
  89             'default': {},
  90             'properties': {
  91                 'runscript': {'type': 'string'},
  92                 'startscript': {'type': 'string'},
  93                 'test': {'type': 'string'},
  94                 'help': {'type': 'string'}
  95             }
  96         },
  97         'docker': {
  98             'type': 'object',
  99             'additionalProperties': False,
  100             'default': {},
  101         }
  102     }
  103 }
  104 
  105 properties = {'container': container_schema}
  106
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/lib/spack/spack/schema/container.py b/lib/spack/spack/schema/container.py
  --- a/lib/spack/spack/schema/container.py
  +++ b/lib/spack/spack/schema/container.py
  @@ -12,8 +12,7 @@
               'type': 'string',
               'enum': ['ubuntu:18.04',
                        'ubuntu:16.04',
  -                     'centos:7',
  -                     'centos:6']
  +                     'centos:7']
           },
           'spack': {
               'type': 'string',
  
verification_info: {"golden_diff": "diff --git a/lib/spack/spack/schema/container.py b/lib/spack/spack/schema/container.py\n--- a/lib/spack/spack/schema/container.py\n+++ b/lib/spack/spack/schema/container.py\n@@ -12,8 +12,7 @@\n             'type': 'string',\n             'enum': ['ubuntu:18.04',\n                      'ubuntu:16.04',\n-                     'centos:7',\n-                     'centos:6']\n+                     'centos:7']\n         },\n         'spack': {\n             'type': 'string',\n", "issue": "CentOS 6 image doesn't build with clingo on Dockerhub\n### Steps to reproduce\r\n\r\nHas to do with failure on centos:6\r\n\r\n```\r\nStep 17/19 : RUN spack spec hdf5+mpi\r\n ---> Running in 8335d48ff53f\r\n==> Warning: Spack will not check SSL certificates. You need to update your Python to enable certificate verification.\r\n==> Warning: Spack will not check SSL certificates. You need to update your Python to enable certificate verification.\r\n==> Warning: the original concretizer is currently being used.\r\n        Upgrade to \"clingo\" at your earliest convenience. The original concretizer will be removed from Spack starting at v0.18.0\r\n==> Error: cannot bootstrap the \"clingo\" Python module from spec \"clingo-bootstrap@spack+python %gcc target=x86_64\"\r\nInput spec\r\n--------------------------------\r\nhdf5+mpi\r\n\r\nConcretized\r\n--------------------------------\r\n==> Bootstrapping clingo from pre-built binaries\r\nThe command 'docker-shell spack spec hdf5+mpi' returned a non-zero code: 3\r\n```\r\n\r\n---\r\n\r\nSo it bootstraps *during* concretization?\n", "before_files": [{"content": "# Copyright 2013-2021 Lawrence Livermore National Security, LLC and other\n# Spack Project Developers. See the top-level COPYRIGHT file for details.\n#\n# SPDX-License-Identifier: (Apache-2.0 OR MIT)\n\"\"\"Schema for the 'container' subsection of Spack environments.\"\"\"\n\n_stages_from_dockerhub = {\n    'type': 'object',\n    'additionalProperties': False,\n    'properties': {\n        'os': {\n            'type': 'string',\n            'enum': ['ubuntu:18.04',\n                     'ubuntu:16.04',\n                     'centos:7',\n                     'centos:6']\n        },\n        'spack': {\n            'type': 'string',\n        },\n    },\n    'required': ['os', 'spack']\n}\n\n_custom_stages = {\n    'type': 'object',\n    'additionalProperties': False,\n    'properties': {\n        'build': {'type': 'string'},\n        'final': {'type': 'string'}\n    },\n    'required': ['build', 'final']\n}\n\n#: List of packages for the schema below\n_list_of_packages = {\n    'type': 'array',\n    'items': {\n        'type': 'string'\n    }\n}\n\n#: Schema for the container attribute included in Spack environments\ncontainer_schema = {\n    'type': 'object',\n    'additionalProperties': False,\n    'properties': {\n        # The recipe formats that are currently supported by the command\n        'format': {\n            'type': 'string',\n            'enum': ['docker', 'singularity']\n        },\n        # Describes the base image to start from and the version\n        # of Spack to be used\n        'images': {'anyOf': [_stages_from_dockerhub, _custom_stages]},\n        # Whether or not to strip installed binaries\n        'strip': {\n            'type': 'boolean',\n            'default': True\n        },\n        # Additional system packages that are needed at runtime\n        'os_packages': {\n            'type': 'object',\n            'properties': {\n                'command': {'type': 'string', 'enum': ['apt', 'yum']},\n                'update': {'type': 'boolean'},\n                'build': _list_of_packages,\n                'final': _list_of_packages\n            },\n            'additionalProperties': False\n        },\n        # Add labels to the image\n        'labels': {\n            'type': 'object',\n        },\n        # Add a custom extra section at the bottom of a stage\n        'extra_instructions': {\n            'type': 'object',\n            'additionalProperties': False,\n            'properties': {\n                'build': {'type': 'string'},\n                'final': {'type': 'string'}\n            }\n        },\n        # Reserved for properties that are specific to each format\n        'singularity': {\n            'type': 'object',\n            'additionalProperties': False,\n            'default': {},\n            'properties': {\n                'runscript': {'type': 'string'},\n                'startscript': {'type': 'string'},\n                'test': {'type': 'string'},\n                'help': {'type': 'string'}\n            }\n        },\n        'docker': {\n            'type': 'object',\n            'additionalProperties': False,\n            'default': {},\n        }\n    }\n}\n\nproperties = {'container': container_schema}\n", "path": "lib/spack/spack/schema/container.py"}], "after_files": [{"content": "# Copyright 2013-2021 Lawrence Livermore National Security, LLC and other\n# Spack Project Developers. See the top-level COPYRIGHT file for details.\n#\n# SPDX-License-Identifier: (Apache-2.0 OR MIT)\n\"\"\"Schema for the 'container' subsection of Spack environments.\"\"\"\n\n_stages_from_dockerhub = {\n    'type': 'object',\n    'additionalProperties': False,\n    'properties': {\n        'os': {\n            'type': 'string',\n            'enum': ['ubuntu:18.04',\n                     'ubuntu:16.04',\n                     'centos:7']\n        },\n        'spack': {\n            'type': 'string',\n        },\n    },\n    'required': ['os', 'spack']\n}\n\n_custom_stages = {\n    'type': 'object',\n    'additionalProperties': False,\n    'properties': {\n        'build': {'type': 'string'},\n        'final': {'type': 'string'}\n    },\n    'required': ['build', 'final']\n}\n\n#: List of packages for the schema below\n_list_of_packages = {\n    'type': 'array',\n    'items': {\n        'type': 'string'\n    }\n}\n\n#: Schema for the container attribute included in Spack environments\ncontainer_schema = {\n    'type': 'object',\n    'additionalProperties': False,\n    'properties': {\n        # The recipe formats that are currently supported by the command\n        'format': {\n            'type': 'string',\n            'enum': ['docker', 'singularity']\n        },\n        # Describes the base image to start from and the version\n        # of Spack to be used\n        'images': {'anyOf': [_stages_from_dockerhub, _custom_stages]},\n        # Whether or not to strip installed binaries\n        'strip': {\n            'type': 'boolean',\n            'default': True\n        },\n        # Additional system packages that are needed at runtime\n        'os_packages': {\n            'type': 'object',\n            'properties': {\n                'command': {'type': 'string', 'enum': ['apt', 'yum']},\n                'update': {'type': 'boolean'},\n                'build': _list_of_packages,\n                'final': _list_of_packages\n            },\n            'additionalProperties': False\n        },\n        # Add labels to the image\n        'labels': {\n            'type': 'object',\n        },\n        # Add a custom extra section at the bottom of a stage\n        'extra_instructions': {\n            'type': 'object',\n            'additionalProperties': False,\n            'properties': {\n                'build': {'type': 'string'},\n                'final': {'type': 'string'}\n            }\n        },\n        # Reserved for properties that are specific to each format\n        'singularity': {\n            'type': 'object',\n            'additionalProperties': False,\n            'default': {},\n            'properties': {\n                'runscript': {'type': 'string'},\n                'startscript': {'type': 'string'},\n                'test': {'type': 'string'},\n                'help': {'type': 'string'}\n            }\n        },\n        'docker': {\n            'type': 'object',\n            'additionalProperties': False,\n            'default': {},\n        }\n    }\n}\n\nproperties = {'container': container_schema}\n", "path": "lib/spack/spack/schema/container.py"}]}