Code review comment for lp:~parthm/bzr/300062-better-handling-for-invalid-ignore-pattern

> Ok, I've looked through this again, and I'd like to suggest a deeper
> implementation strategy.

Thanks for the review and comment. I have cleanup the error handling now.
Basically, the following is done:
1. General regex compile failure now raises InvalidPattern error.
2. Invalid pattern errors are now raised only by bzrlib.globbing.Globster.match
3. `bzr ignore PATTERN..` skips invalid patterns passed. Existing errors are handled by bzrlib.globbing.Globster.match.