Fisheye should handle this specific git error - blame::find_origin (D)- more gracefully

Problem Definition

• During indexing of a repo Fisheye will use git to calculate blame
• If git is unable to find blame origin for a commit it may return the following fatal: internal error in blame::find_origin (D)
• The index of the repo will not complete if this error is encountered

Suggested Solution

• Fisheye should be able to handle this error more gracefully with perhaps a clear call to action to disable blame calculation at the appropriate level ie. per repo by disabling "store diff info" setting or system wide via a system property - fisheye.blame.calc.enable

Workaround

• Disabling blame calculation should allow the repo to index successfully with the caveat that LoC will also be disabled