run-tests: move build/ directory to HGTMP
Before, running a test would give you a build/ directory in the root
of your Mercurial source tree. The directory had a full copy of the
the source, so a grep in '**/*.py' would find files inside build/.
[ original upstream description ]
syntax: glob
*.pyc
*.pyo
*~
*.swp
*.orig
*.rej
.DS_Store
build/*
MANIFEST