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()

```

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'})

{"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"}]}