run-tests: always define a custom-bin directory
We are always generating `python` / `python3` executable and we will soon often
generate a `hg` executable. So let's always make it a thing. This will help us
to make sure we have the appropriate binary available to all script. On both
linux and Windows.
Differential Revision: https://phab.mercurial-scm.org/D11044
$ hg init
$ echo a > a
$ hg ci -Ama
adding a
$ hg an a
0: a
$ hg --config ui.strict=False an a
0: a
$ echo "[ui]" >> $HGRCPATH
$ echo "strict=True" >> $HGRCPATH
$ hg an a
hg: unknown command 'an'
(use 'hg help' for a list of commands)
[10]
$ hg annotate a
0: a
should succeed - up is an alias, not an abbreviation
$ hg up
0 files updated, 0 files merged, 0 files removed, 0 files unresolved