[PATCH] gitk: properly deal with tag names containing / (slash)

[PATCH] gitk: properly deal with tag names containing / (slash)

When creating a tag through gitk, and the tag name includes a slash (or
slashes), gitk errors out in a popup window.  This patch makes gitk use
'git tag' to create the tag instead of modifying files in refs/tags/,
which fixes the issue; if 'git tag' throws an error, gitk pops up with
the error message.

The problem was reported by Frédéric Brière through
 http://bugs.debian.org/464104

Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>