Maintenance release for 2.51 branch.
Fixes:
- Git config log.showSignature breaks revision grid - Issue 5179
Fixes (Mono specific):
- Settings causes crash under linux/mono - Issue 5311
- Git Extension crashes when trying to access settings page in Ubuntu 16.04 - Issue 5187
- Diff view options are positioned wrong, cannot be selected under linux/mono - Issue 4978