Isolate test suite from global git config settings.

Test.hs

@@ -112,6 +112,7 @@ optParser = TestOptions
 runner :: Maybe (TestOptions -> IO ())
 runner = Just $ \opts -> do
 	ensuretmpdir
+	isolateGitConfig
 	crippledfilesystem <- Annex.Init.probeCrippledFileSystem' tmpdir
 	case tryIngredients ingredients (tastyOptionSet opts) (tests crippledfilesystem opts) of
 		Nothing -> error "No tests found!?"
@@ -1787,6 +1788,15 @@ ensuretmpdir = do
 	e <- doesDirectoryExist tmpdir
 	unless e $
 		createDirectory tmpdir
+	
+{- Prevent global git configs from affecting the test suite. -}
+isolateGitConfig :: IO ()
+isolateGitConfig = do
+	let tmphome = tmpdir </> "home"
+	createDirectoryIfMissing False tmphome
+	Utility.Env.setEnv "HOME" tmphome True
+	Utility.Env.setEnv "XDG_CONFIG_HOME" tmphome True
+	Utility.Env.setEnv "GIT_CONFIG_NOSYSTEM" "1" True
 
 cleanup :: FilePath -> IO ()
 cleanup = cleanup' False

debian/changelog

@@ -10,6 +10,7 @@ git-annex (6.20160419) UNRELEASED; urgency=medium
     to refer to a file.
   * Fix bug that prevented annex.sshcaching=false configuration from taking
     effect when on a crippled filesystem. Thanks, divergentdave.
+  * Isolate test suite from global git config settings.
 
  -- Joey Hess <id@joeyh.name>  Tue, 19 Apr 2016 12:57:15 -0400
 

doc/bugs/Three_tests_fail_when_annex.backends_is_defined.mdwn

@@ -105,3 +105,7 @@ found a bug report from you on
 be related, but I don't know if that's the case. The newest version I'm 
 able to build is 5.20150219, somewhere after that various things start 
 to fail.
+
+> [[fixed|done]]; I found a way to isolate the test suite from global git
+> configs, by setting `GIT_CONFIG_NOSYSTEM` and also setting
+> `HOME` and `XDG_CONFIG_HOME` to an empty directory. --[[Joey]]