Use git-tag in git-cvsimport

Currently git-cvsimport tries to create tag objects directly via git-mktag
in a very broken way, e.g the stuff it writes into the tagger field of
the tag object doesn't really resemble the GIT_COMMITTER_IDENT. This makes
gitweb and possibly other tools that try to interpret tag objects to be
confused about tag date and authorship.

Fix this by calling git-tag instead. This also has a nice side effect of
not creating the tag object but only the lightweight tag as that's the only
thing CVS has anyways.

Signed-off-by: Elvis Pranskevichus <el@prans.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-cvsimport.perl

@@ -772,30 +772,8 @@ sub commit {
 		$xtag =~ tr/_/\./ if ( $opt_u );
 		$xtag =~ s/[\/]/$opt_s/g;
 
-		my $pid = open2($in, $out, 'git-mktag');
+		system('git-tag', $xtag, $cid) == 0
-		print $out "object $cid\n".
-		    "type commit\n".
-		    "tag $xtag\n".
-		    "tagger $author_name <$author_email>\n"
-		    or die "Cannot create tag object $xtag: $!\n";
-		close($out)
-		    or die "Cannot create tag object $xtag: $!\n";
-
-		my $tagobj = <$in>;
-		chomp $tagobj;
-
-		if ( !close($in) or waitpid($pid, 0) != $pid or
-		     $? != 0 or $tagobj !~ /^[0123456789abcdef]{40}$/ ) {
-		    die "Cannot create tag object $xtag: $!\n";
-	        }
-		
-
-		open(C,">$git_dir/refs/tags/$xtag")
 			or die "Cannot create tag $xtag: $!\n";
-		print C "$tagobj\n"
-			or die "Cannot write tag $xtag: $!\n";
-		close(C)
-			or die "Cannot write tag $xtag: $!\n";
 
 		print "Created tag '$xtag' on '$branch'\n" if $opt_v;
 	}