test-extension: fix disabled extension tests for run-tests.py --local
One test that requires inserting a broken extension into hgext does this
by modifying PYTHONPATH. This doesn't work when run with --local because
the 'hg' script being used is in the same directory as the local hgext.
Instead of modifying PYTHONPATH, a secondary extension is enabled using
--config that inserts the dummy hgext at the beginning of sys.path,
before the script's path.
% no bookmarks
no bookmarks set
% set bookmark X
% list bookmarks
* X -1:000000000000
% update to bookmark X
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
% list bookmarks
* X -1:000000000000
% rename
% list bookmarks
* Z -1:000000000000
% new bookmark Y
% list bookmarks
* Y -1:000000000000
Z -1:000000000000
% commit
% list bookmarks
* Y 0:719295282060
Z -1:000000000000
% delete bookmarks
% list bookmarks
no bookmarks set
% update to tip
0 files updated, 0 files merged, 0 files removed, 0 files unresolved