graphmod: disable graph styling when HGPLAIN is set (issue5212)
Produce stable output for tools to rely on by hardcoding all edge styles to
"|". This ensures that any tool parsing the output of hg log -G still gets the
same behaviour as pre-3.8 releases.
https://bz.mercurial-scm.org/1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..