D376: filemerge: extract `_picklabels` as a helper function

[phillco (Phil Cohen)]

phillco added inline comments.

INLINE COMMENTS

> martinvonz wrote in simplemerge.py:411-423
>   def _picklabels(defaults, overrides):
>     if len(overrides) > 3:
>           raise error.Abort(_("can only specify three labels."))
>     result = defaults[:]
>     for i, override in enumerate(overrides):
>       result[i] = override
>     return result
> 
> no?

I think so, not sure why the original was so weird. I'll replace it.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D376

To: phillco, #hg-reviewers
Cc: martinvonz, mercurial-devel