Log Message:
git-base: Use bash to run tests

At least with NetBSD (9.99.17) sh(1) the `streaming support for --stdin'
test of t0008-ignores.sh hangs.  Force to use bash for tests and add it as a
test dependency. (This needs to be investigate further.)

The entire test suite is now runs but at least on NetBSD 9.99.17
t0301-credential-cache.sh test 29 `use user socket if user directory
exists' and test 30 `use user socket if user directory is a symlink to
a directory' fail.