cvsserver: add option to configure commit message

cvsserver annotates each commit message by "via git-CVS emulator". This is
made configurable via gitcvs.commitmsgannotation.

Signed-off-by: Fabian Emmes <fabian.emmes@rwth-aachen.de>
Signed-off-by: Lars Noschinski <lars@public.noschinski.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -723,6 +723,10 @@ gc.rerereunresolved::
 	kept for this many days when 'git-rerere gc' is run.
 	The default is 15 days.  See linkgit:git-rerere[1].
 
+gitcvs.commitmsgannotation::
+	Append this string to each commit message. Set to empty string
+	to disable this feature. Defaults to "via git-CVS emulator".
+
 gitcvs.enabled::
 	Whether the CVS server interface is enabled for this repository.
 	See linkgit:git-cvsserver[1].

git-cvsserver.perl

@@ -1358,7 +1358,13 @@ sub req_ci
     # write our commit message out if we have one ...
     my ( $msg_fh, $msg_filename ) = tempfile( DIR => $TEMP_DIR );
     print $msg_fh $state->{opt}{m};# if ( exists ( $state->{opt}{m} ) );
-    print $msg_fh "\n\nvia git-CVS emulator\n";
+    if ( defined ( $cfg->{gitcvs}{commitmsgannotation} ) ) {
+        if ($cfg->{gitcvs}{commitmsgannotation} !~ /^\s*$/ ) {
+            print $msg_fh "\n\n".$cfg->{gitcvs}{commitmsgannotation}."\n"
+        }
+    } else {
+        print $msg_fh "\n\nvia git-CVS emulator\n";
+    }
     close $msg_fh;
 
     my $commithash = `git-commit-tree $treehash -p $parenthash < $msg_filename`;