fix: determine fixer tool failure by exit code instead of stderr...
fix: determine fixer tool failure by exit code instead of stderr
This seems like the more natural thing, and it probably should have been this
way to beign with. It is more flexible because it allows tools to emit
diagnostic information while also modifying a file. An example would be an
automatic code formatter that also prints any remaining lint issues.
Differential Revision:
https://phab.mercurial-scm.org/D4158
