Reference Browser: Try exact match first when selecting ref node

Fix selecting wrong branch when both refs/original/refs/remotes/origin/master and refs/remotes/origin/master exist

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Synced TortoiseGitIDiff with TortoiseSVN

Based on TortoiseSVN revision #24532.

Signed-off-by: Sven Strickroth <email@cs-ware.de>