git-cvsserver: allow regex metacharacters in CVSROOT

When run in a repository with a path name containing regex metacharacters
(e.g. +), git-cvsserver failed to split the client request into CVSROOT
and module.  Now metacharacters are disabled for the value of CVSROOT in
the perl regex so that directory names containing metacharacters are
handled properly.

Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-cvsserver.perl

@@ -388,7 +388,7 @@ sub req_Directory
     $state->{localdir} = $data;
     $state->{repository} = $repository;
     $state->{path} = $repository;
-    $state->{path} =~ s/^$state->{CVSROOT}\///;
+    $state->{path} =~ s/^\Q$state->{CVSROOT}\E\///;
     $state->{module} = $1 if ($state->{path} =~ s/^(.*?)(\/|$)//);
     $state->{path} .= "/" if ( $state->{path} =~ /\S/ );