git-svn: don't blindly append '*' to branch/tags config

git-svn: don't blindly append '*' to branch/tags config

Previously, git-svn would blindly append '*' even if it was specified by
the user during initialization (for certain SVN setups, it is
necessary).

Now, the following command will work correctly:

  git svn init -T trunk/docutils \
               -t 'tags/*/docutils' \
               -b 'branches/*/docutils' \
               svn://svn.berlios.de/docutils

Thanks to martin f krafft for the bug report:
> My git-svn target configuration is
>
>   [svn-remote "svn"]
>     url = svn://svn.berlios.de/docutils
>     fetch = trunk/docutils:refs/remotes/trunk
>     branches = branches/*/docutils:refs/remotes/*
>     tags = tags/*/docutils:refs/remotes/tags/*
>
> Unfortunately, when I run
>
>   git-svn init -T trunk/docutils -t 'tags/*/docutils'
>    -b 'branches/*/docutils'
>
> then I get (note the two asterisks on the left hand side):
>
>     branches = branches/*/docutils/*:refs/remotes/*
>     tags = tags/*/docutils/*:refs/remotes/tags/*
>
> I took a brief stab at the code but I can't even figure out where
> the /* is appended, so I defer to you.
>
> It should be trivial to keep git-svn from appending /* if the left
> side already contains an asterisk.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Tested-by: martin f krafft <madduck@madduck.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>