Removed support for git versions older than 2.1

debian oldoldstable has 2.1, and that's what i386ancient uses. It would be
better to require git 2.2, which is needed to use adjusted branches, but
can't do that w/o losing support for some old linux kernels or a
complicated git backport.

Git/Branch.hs

@@ -15,7 +15,6 @@ import Git.Sha
 import Git.Command
 import qualified Git.Config
 import qualified Git.Ref
-import qualified Git.BuildVersion
 
 {- The currently checked out branch.
  -
@@ -125,8 +124,7 @@ data CommitMode = ManualCommit | AutomaticCommit
 {- Prevent signing automatic commits. -}
 applyCommitMode :: CommitMode -> [CommandParam] -> [CommandParam]
 applyCommitMode commitmode ps
-	| commitmode == AutomaticCommit && not (Git.BuildVersion.older "2.0.0") =
-		Param "--no-gpg-sign" : ps
+	| commitmode == AutomaticCommit = Param "--no-gpg-sign" : ps
 	| otherwise = ps
 
 {- Some versions of git commit-tree honor commit.gpgsign themselves,