filemerge: when merge tool uses $output, don't leave markers in $local...
filemerge: when merge tool uses $output, don't leave markers in $local
As explained in the previous patch, we incorrectly leave conflict
markers in both `$local` and `$output` since D12190. I don't
understand why it broke but the fix is simple and clear after all the
recent refactoring.
Differential Revision:
https://phab.mercurial-scm.org/D12379
