filemerge: when not keeping premerge, don't write markers to context When premerge is enabled (as it is for non-binary inputs by default) and the markers are not kept, we currently still write it to the output context and then restore the previous content right after. With the refactoring in the previous patch, we can easily avoid that step and instead write the output in the opposite case (i.e. when it's successful or when the markers are supposed to be kept). Differential Revision: https://phab.mercurial-scm.org/D12149

#require docutils gettext

Error: the current ro localization has some rst defects exposed by
moving pager to core. These two warnings about references are expected
until the localization is corrected.
  $ $TESTDIR/check-gendoc ro
  checking for parse errors
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.