put in workaround for strange version of git on the autobuilder

Build/Configure.hs

@@ -94,12 +94,15 @@ getUpgradeLocation = do
 	return $ Config "upgradelocation" $ MaybeStringConfig e
 
 getGitVersion :: Test
-getGitVersion = do
-	v <- Git.Version.installed
-	let oldestallowed = Git.Version.normalize "1.7.1.0"
-	when (v < oldestallowed) $
-		error $ "installed git version " ++ show v ++ " is too old! (Need " ++ show oldestallowed ++ " or newer)"
-	return $ Config "gitversion" $ StringConfig $ show v
+getGitVersion = go =<< getEnv "FORCE_GIT_VERSION"
+  where
+	go (Just s) = return $ Config "gitversion" $ StringConfig s
+	go Nothing = do
+		v <- Git.Version.installed
+		let oldestallowed = Git.Version.normalize "1.7.1.0"
+		when (v < oldestallowed) $
+			error $ "installed git version " ++ show v ++ " is too old! (Need " ++ show oldestallowed ++ " or newer)"
+		return $ Config "gitversion" $ StringConfig $ show v
 
 checkWgetQuietProgress :: Test
 checkWgetQuietProgress = Config "wgetquietprogress" . BoolConfig

standalone/windows/build.sh

@@ -11,10 +11,6 @@ set -e
 
 PATH="/c/Program Files (x86)/NSIS:/c/msysgit/cmd:/c/msysgit/bin:$PATH"
 
-git --version || true
-which git || true
-/c/msysgit/cmd/git --version || true
-
 # Run a command with the cygwin environment available.
 # However, programs not from cygwin are preferred.
 withcyg () {
@@ -27,6 +23,10 @@ withcygpreferred () {
 # This tells git-annex where to upgrade itself from.
 UPGRADE_LOCATION=http://downloads.kitenet.net/git-annex/windows/current/git-annex-installer.exe
 
+# This can be used to force git-annex to build supporting a particular
+# version of git, instead of the version installed at build time.
+FORCE_GIT_VERSION=1.9.5
+
 # Uncomment to get rid of cabal installed libraries.
 #rm -rf /c/Users/jenkins/AppData/Roaming/cabal /c/Users/jenkins/AppData/Roaming/ghc