Update to jgit-describe with less NPEs
Update to jgit-describe with less NPEs

Change-Id: I0abeee0c308a4bef7822ce901d358401d055f97a
Reviewed-on: http://gerrit.dmdirc.com/2329
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <711c73f64afdce07b7e38039a96d2224209e9a6c@dmdirc.com>

DMDirc/Util