prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  `spack checksum` finds wrong URLs
  I was having some problems getting spack to find the correct URL for files.
  
  With these settings
  
  ``` python
      homepage = "http://fishshell.com/"
      url      = "http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz"
      list_url = homepage
  ```
  
  I get the following result (with wrong URLs):
  
  ``` sh
  $ spack checksum fish
  ==> Found 5 versions of fish.
    2.2.0     http://fishshell.com/fish-2.2.0.tar.gz
    2.1.2     http://fishshell.com/fish-2.1.2.tar.gz
    2.1.1     http://fishshell.com/fish-2.1.1.tar.gz
    2.1.0     http://fishshell.com/fish-2.1.0.tar.gz
    2.0.0     http://fishshell.com/fish-2.0.0.tar.gz
  
  How many would you like to checksum? (default is 5, q to abort)
  ==> Downloading...
  ==> Trying to fetch from http://fishshell.com/fish-2.2.0.tar.gz
  
  curl: (22) The requested URL returned error: 404 Not Found
  ==> Fetching from http://fishshell.com/fish-2.2.0.tar.gz failed.
  ==> Error: All fetchers failed for spack-stage-Slflbn
  ```
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `var/spack/repos/builtin/packages/fish/package.py`
  Content:
  ```
  1 ##############################################################################
  2 # Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
  3 # Produced at the Lawrence Livermore National Laboratory.
  4 #
  5 # This file is part of Spack.
  6 # Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
  7 # LLNL-CODE-647188
  8 #
  9 # For details, see https://github.com/llnl/spack
  10 # Please also see the LICENSE file for our notice and the LGPL.
  11 #
  12 # This program is free software; you can redistribute it and/or modify
  13 # it under the terms of the GNU Lesser General Public License (as
  14 # published by the Free Software Foundation) version 2.1, February 1999.
  15 #
  16 # This program is distributed in the hope that it will be useful, but
  17 # WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
  18 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
  19 # conditions of the GNU Lesser General Public License for more details.
  20 #
  21 # You should have received a copy of the GNU Lesser General Public
  22 # License along with this program; if not, write to the Free Software
  23 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  24 ##############################################################################
  25 from spack import *
  26 
  27 
  28 class Fish(Package):
  29     """fish is a smart and user-friendly command line shell for OS X, Linux, and
  30     the rest of the family.
  31     """
  32 
  33     homepage = "http://fishshell.com/"
  34     url      = "http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz"
  35     list_url = "http://fishshell.com/files/"
  36     list_depth = 2
  37 
  38     version('2.2.0', 'a76339fd14ce2ec229283c53e805faac48c3e99d9e3ede9d82c0554acfc7b77a')
  39 
  40     def install(self, spec, prefix):
  41         configure('--prefix=%s' % prefix)
  42 
  43         make()
  44         make("install")
  45
  ```
  --- 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/var/spack/repos/builtin/packages/fish/package.py b/var/spack/repos/builtin/packages/fish/package.py
  --- a/var/spack/repos/builtin/packages/fish/package.py
  +++ b/var/spack/repos/builtin/packages/fish/package.py
  @@ -32,8 +32,7 @@
   
       homepage = "http://fishshell.com/"
       url      = "http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz"
  -    list_url = "http://fishshell.com/files/"
  -    list_depth = 2
  +    list_url = "http://fishshell.com/"
   
       version('2.2.0', 'a76339fd14ce2ec229283c53e805faac48c3e99d9e3ede9d82c0554acfc7b77a')
  
verification_info: {"golden_diff": "diff --git a/var/spack/repos/builtin/packages/fish/package.py b/var/spack/repos/builtin/packages/fish/package.py\n--- a/var/spack/repos/builtin/packages/fish/package.py\n+++ b/var/spack/repos/builtin/packages/fish/package.py\n@@ -32,8 +32,7 @@\n \n     homepage = \"http://fishshell.com/\"\n     url      = \"http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz\"\n-    list_url = \"http://fishshell.com/files/\"\n-    list_depth = 2\n+    list_url = \"http://fishshell.com/\"\n \n     version('2.2.0', 'a76339fd14ce2ec229283c53e805faac48c3e99d9e3ede9d82c0554acfc7b77a')\n", "issue": "`spack checksum` finds wrong URLs\nI was having some problems getting spack to find the correct URL for files.\n\nWith these settings\n\n``` python\n    homepage = \"http://fishshell.com/\"\n    url      = \"http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz\"\n    list_url = homepage\n```\n\nI get the following result (with wrong URLs):\n\n``` sh\n$ spack checksum fish\n==> Found 5 versions of fish.\n  2.2.0     http://fishshell.com/fish-2.2.0.tar.gz\n  2.1.2     http://fishshell.com/fish-2.1.2.tar.gz\n  2.1.1     http://fishshell.com/fish-2.1.1.tar.gz\n  2.1.0     http://fishshell.com/fish-2.1.0.tar.gz\n  2.0.0     http://fishshell.com/fish-2.0.0.tar.gz\n\nHow many would you like to checksum? (default is 5, q to abort)\n==> Downloading...\n==> Trying to fetch from http://fishshell.com/fish-2.2.0.tar.gz\n\ncurl: (22) The requested URL returned error: 404 Not Found\n==> Fetching from http://fishshell.com/fish-2.2.0.tar.gz failed.\n==> Error: All fetchers failed for spack-stage-Slflbn\n```\n\n", "before_files": [{"content": "##############################################################################\n# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.\n# Produced at the Lawrence Livermore National Laboratory.\n#\n# This file is part of Spack.\n# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.\n# LLNL-CODE-647188\n#\n# For details, see https://github.com/llnl/spack\n# Please also see the LICENSE file for our notice and the LGPL.\n#\n# This program is free software; you can redistribute it and/or modify\n# it under the terms of the GNU Lesser General Public License (as\n# published by the Free Software Foundation) version 2.1, February 1999.\n#\n# This program is distributed in the hope that it will be useful, but\n# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF\n# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and\n# conditions of the GNU Lesser General Public License for more details.\n#\n# You should have received a copy of the GNU Lesser General Public\n# License along with this program; if not, write to the Free Software\n# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA\n##############################################################################\nfrom spack import *\n\n\nclass Fish(Package):\n    \"\"\"fish is a smart and user-friendly command line shell for OS X, Linux, and\n    the rest of the family.\n    \"\"\"\n\n    homepage = \"http://fishshell.com/\"\n    url      = \"http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz\"\n    list_url = \"http://fishshell.com/files/\"\n    list_depth = 2\n\n    version('2.2.0', 'a76339fd14ce2ec229283c53e805faac48c3e99d9e3ede9d82c0554acfc7b77a')\n\n    def install(self, spec, prefix):\n        configure('--prefix=%s' % prefix)\n\n        make()\n        make(\"install\")\n", "path": "var/spack/repos/builtin/packages/fish/package.py"}], "after_files": [{"content": "##############################################################################\n# Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.\n# Produced at the Lawrence Livermore National Laboratory.\n#\n# This file is part of Spack.\n# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.\n# LLNL-CODE-647188\n#\n# For details, see https://github.com/llnl/spack\n# Please also see the LICENSE file for our notice and the LGPL.\n#\n# This program is free software; you can redistribute it and/or modify\n# it under the terms of the GNU Lesser General Public License (as\n# published by the Free Software Foundation) version 2.1, February 1999.\n#\n# This program is distributed in the hope that it will be useful, but\n# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF\n# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and\n# conditions of the GNU Lesser General Public License for more details.\n#\n# You should have received a copy of the GNU Lesser General Public\n# License along with this program; if not, write to the Free Software\n# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA\n##############################################################################\nfrom spack import *\n\n\nclass Fish(Package):\n    \"\"\"fish is a smart and user-friendly command line shell for OS X, Linux, and\n    the rest of the family.\n    \"\"\"\n\n    homepage = \"http://fishshell.com/\"\n    url      = \"http://fishshell.com/files/2.2.0/fish-2.2.0.tar.gz\"\n    list_url = \"http://fishshell.com/\"\n\n    version('2.2.0', 'a76339fd14ce2ec229283c53e805faac48c3e99d9e3ede9d82c0554acfc7b77a')\n\n    def install(self, spec, prefix):\n        configure('--prefix=%s' % prefix)\n\n        make()\n        make(\"install\")\n", "path": "var/spack/repos/builtin/packages/fish/package.py"}]}