prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  v1.6.0 will break if download scripts are added to version.txt in master
  We have now done this twice (see #180 and #199).
  
  In v1.6.0 `__init__.py` line 16: `MASTER = True`. This results in the retriever always checking `master` for `version.txt` and discovering scripts that it doesn't know how to handle. In the future, the retriever will handle this gracefully thanks to #204, but it's unclear how we should go about introducing the download only functionality since it will break a number of existing installations.
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `scripts/MammalSuperTree.py`
  Content:
  ```
  1 #retriever
  2 from retriever.lib.templates import DownloadOnlyTemplate
  3 
  4 SCRIPT = DownloadOnlyTemplate(name="Mammal Super Tree",
  5                               shortname='mammsupertree',
  6                               ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',
  7                               citation = "Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x",
  8                               description="Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549",
  9                               urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})
  10
  ```
  --- 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/scripts/MammalSuperTree.py b/scripts/MammalSuperTree.py
  --- a/scripts/MammalSuperTree.py
  +++ b/scripts/MammalSuperTree.py
  @@ -1,9 +1,22 @@
   #retriever
  -from retriever.lib.templates import DownloadOnlyTemplate
  -
  -SCRIPT = DownloadOnlyTemplate(name="Mammal Super Tree",
  -                              shortname='mammsupertree',
  -                              ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',
  -                              citation = "Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x",
  -                              description="Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549",
  -                              urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})
  +from retriever import VERSION
  +if (VERSION == 'v1.6') or (VERSION == 'v1.6.0'):
  +    #If v1.6 is running use a dummy script to avoid retriever errors
  +    #See https://github.com/weecology/retriever/issues/208 for details
  +    from retriever.lib.templates import Script
  +    class main(Script):
  +        def __init(self):
  +            Script.__init__(self,
  +                            name="Mammal Super Tree",
  +                            shortname='mammsupertree',
  +                           )
  +    SCRIPT = main()
  +else:
  +    #For all versions other than 1.6 run as normal
  +    from retriever.lib.templates import DownloadOnlyTemplate
  +    SCRIPT = DownloadOnlyTemplate(name="Mammal Super Tree",
  +                                  shortname='mammsupertree',
  +                                  ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',
  +                                  citation = "Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x",
  +                                  description="Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549",
  +                                  urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})
  
verification_info: {"golden_diff": "diff --git a/scripts/MammalSuperTree.py b/scripts/MammalSuperTree.py\n--- a/scripts/MammalSuperTree.py\n+++ b/scripts/MammalSuperTree.py\n@@ -1,9 +1,22 @@\n #retriever\n-from retriever.lib.templates import DownloadOnlyTemplate\n-\n-SCRIPT = DownloadOnlyTemplate(name=\"Mammal Super Tree\",\n-                              shortname='mammsupertree',\n-                              ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',\n-                              citation = \"Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x\",\n-                              description=\"Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549\",\n-                              urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})\n+from retriever import VERSION\n+if (VERSION == 'v1.6') or (VERSION == 'v1.6.0'):\n+    #If v1.6 is running use a dummy script to avoid retriever errors\n+    #See https://github.com/weecology/retriever/issues/208 for details\n+    from retriever.lib.templates import Script\n+    class main(Script):\n+        def __init(self):\n+            Script.__init__(self,\n+                            name=\"Mammal Super Tree\",\n+                            shortname='mammsupertree',\n+                           )\n+    SCRIPT = main()\n+else:\n+    #For all versions other than 1.6 run as normal\n+    from retriever.lib.templates import DownloadOnlyTemplate\n+    SCRIPT = DownloadOnlyTemplate(name=\"Mammal Super Tree\",\n+                                  shortname='mammsupertree',\n+                                  ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',\n+                                  citation = \"Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x\",\n+                                  description=\"Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549\",\n+                                  urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})\n", "issue": "v1.6.0 will break if download scripts are added to version.txt in master\nWe have now done this twice (see #180 and #199).\n\nIn v1.6.0 `__init__.py` line 16: `MASTER = True`. This results in the retriever always checking `master` for `version.txt` and discovering scripts that it doesn't know how to handle. In the future, the retriever will handle this gracefully thanks to #204, but it's unclear how we should go about introducing the download only functionality since it will break a number of existing installations.\n\n", "before_files": [{"content": "#retriever\nfrom retriever.lib.templates import DownloadOnlyTemplate\n\nSCRIPT = DownloadOnlyTemplate(name=\"Mammal Super Tree\",\n                              shortname='mammsupertree',\n                              ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',\n                              citation = \"Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x\",\n                              description=\"Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549\",\n                              urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})\n", "path": "scripts/MammalSuperTree.py"}], "after_files": [{"content": "#retriever\nfrom retriever import VERSION\nif (VERSION == 'v1.6') or (VERSION == 'v1.6.0'):\n    #If v1.6 is running use a dummy script to avoid retriever errors\n    #See https://github.com/weecology/retriever/issues/208 for details\n    from retriever.lib.templates import Script\n    class main(Script):\n        def __init(self):\n            Script.__init__(self,\n                            name=\"Mammal Super Tree\",\n                            shortname='mammsupertree',\n                           )\n    SCRIPT = main()\nelse:\n    #For all versions other than 1.6 run as normal\n    from retriever.lib.templates import DownloadOnlyTemplate\n    SCRIPT = DownloadOnlyTemplate(name=\"Mammal Super Tree\",\n                                  shortname='mammsupertree',\n                                  ref='http://doi.org/10.1111/j.1461-0248.2009.01307.x',\n                                  citation = \"Fritz, S. A., Bininda-Emonds, O. R. P. and Purvis, A. (2009), Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters, 12: 538-549. doi:10.1111/j.1461-0248.2009.01307.x\",\n                                  description=\"Mammal Super Tree from Fritz, S.A., O.R.P Bininda-Emonds, and A. Purvis. 2009. Geographical variation in predictors of mammalian extinction risk: big is bad, but only in the tropics. Ecology Letters 12:538-549\",\n                                  urls ={'mammal_super_tree_fritz2009.tre': 'http://onlinelibrary.wiley.com/store/10.1111/j.1461-0248.2009.01307.x/asset/supinfo/ELE_1307_sm_SA1.tre?v=1&s=366b28651a9b5d1a3148ef9a8620f8aa31a7df44'})\n", "path": "scripts/MammalSuperTree.py"}]}