Check git version at runtime, rather than assuming it will be the same as the git version used at build time when running git-checkattr and git-branch remove.

It's ok to probe every time for git-branch remove because that's
run quite rarely. For git-checkattr, it's run only once, when
starting the --batch mode, and so again the overhead is pretty minimal.

This leaves 2 places where the build version is still used.
git merge might be interactive or fail if one skews, and --no-gpg-sign
might not be pased, or might be passed to a git that doesn't understand it
if the other skews. It seems a little expensive to check the git version
each time these are used.

This doesn't seem likely to cause many problems, at least compared with
check-attr hanging on skew.

Git/CheckAttr.hs

@@ -10,12 +10,12 @@ module Git.CheckAttr where
 import Common
 import Git
 import Git.Command
-import qualified Git.BuildVersion
+import qualified Git.Version
 import qualified Utility.CoProcess as CoProcess
 
 import System.IO.Error
 
-type CheckAttrHandle = (CoProcess.CoProcessHandle, [Attr], String)
+type CheckAttrHandle = (CoProcess.CoProcessHandle, [Attr], Bool, String)
 
 type Attr = String
 
@@ -25,7 +25,8 @@ checkAttrStart :: [Attr] -> Repo -> IO CheckAttrHandle
 checkAttrStart attrs repo = do
 	currdir <- getCurrentDirectory
 	h <- CoProcess.rawMode =<< gitCoProcessStart True params repo
-	return (h, attrs, currdir)
+	oldgit <- Git.Version.older "1.7.7"
+	return (h, attrs, oldgit, currdir)
   where
 	params =
 		[ Param "check-attr" 
@@ -34,11 +35,11 @@ checkAttrStart attrs repo = do
 		[ Param "--" ]
 
 checkAttrStop :: CheckAttrHandle -> IO ()
-checkAttrStop (h, _, _) = CoProcess.stop h
+checkAttrStop (h, _, _, _) = CoProcess.stop h
 
 {- Gets an attribute of a file. -}
 checkAttr :: CheckAttrHandle -> Attr -> FilePath -> IO String
-checkAttr (h, attrs, currdir) want file = do
+checkAttr (h, attrs, oldgit, currdir) want file = do
 	pairs <- CoProcess.query h send (receive "")
 	let vals = map snd $ filter (\(attr, _) -> attr == want) pairs
 	case vals of
@@ -81,7 +82,6 @@ checkAttr (h, attrs, currdir) want file = do
 	 - With newer git, git check-attr chokes on some absolute
 	 - filenames, and the bugs that necessitated them were fixed,
 	 - so use relative filenames. -}
-	oldgit = Git.BuildVersion.older "1.7.7"
 	file'
 		| oldgit = absPathFrom currdir file
 		| otherwise = relPathDirToFile currdir $ absPathFrom currdir file

Git/Remote/Remove.hs

@@ -13,15 +13,17 @@ import Common
 import Git
 import Git.Types
 import qualified Git.Command
-import qualified Git.BuildVersion
+import qualified Git.Version
 
 remove :: RemoteName -> Repo -> IO ()
-remove remotename = Git.Command.run
-	[ Param "remote"
-	-- name of this subcommand changed
-	, Param $
-		if Git.BuildVersion.older "1.8.0"
-			then "rm"
-			else "remove"
-	, Param remotename
-	]
+remove remotename r = do
+	old <- Git.Version.older "1.8.0"
+	Git.Command.run
+		[ Param "remote"
+		-- name of this subcommand changed
+		, Param $
+			if old
+				then "rm"
+				else "remove"
+		, Param remotename
+		] r

Git/Version.hs

@@ -7,6 +7,7 @@
 
 module Git.Version (
 	installed,
+	older,
 	normalize,
 	GitVersion,
 ) where
@@ -22,3 +23,8 @@ installed = normalize . extract <$> readProcess "git" ["--version"]
 	extract s = case lines s of
 		[] -> ""
 		(l:_) -> unwords $ drop 2 $ words l
+
+older :: String -> IO Bool
+older n = do
+	v <- installed
+	return $ v < normalize n 

debian/changelog

@@ -9,6 +9,9 @@ git-annex (5.20141232) UNRELEASED; urgency=medium
   * Android: Provide a version built with -fPIE -pie to support Android 5.0.
   * sync: Fix an edge case where syncing in a bare repository would try to
     merge and so fail.
+  * Check git version at runtime, rather than assuming it will be the same
+    as the git version used at build time when running git-checkattr and
+    git-branch remove.
 
  -- Joey Hess <id@joeyh.name>  Fri, 02 Jan 2015 13:35:13 -0400