copyfiles: deal with existing file when hardlinking
If the hardlinking fails, we fallback to `shutil.copy`, but do not consider
future hardlinking doomed.
This is a slight improvement from the current situation, we still avoid
hardliking in a case we might be able to do it. However this does not have an
impact of the rest of the operation.
(This is an opportunity improvement while looking at something next to that.)
Differential Revision: https://phab.mercurial-scm.org/D10841
#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.