graft: test coverage of grafts and how merges can break duplicate detection
This demonstrates unfortunate behaviour: extending the graft range cause the
graft to behave differently. When the graft range includes a merge, we fail to
detect duplicates that are ancestors of the merge.
#if no-windows no-osx
$ mkdir -p xdgconf/hg
$ echo '[ui]' > xdgconf/hg/hgrc
$ echo 'username = foobar' >> xdgconf/hg/hgrc
$ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
$ unset HGRCPATH
$ hg config ui.username
foobar
#endif