Fix off-by-three error

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fixed issue #2158: TortoiseGit sometimes crashes when doing Sync > Pull

Revert "SyncDlg: Get all refs in new thread to avoid blocking UI"

This reverts commit 294a6903a8356c042885720f592b14d1b48447dd.

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>