t3200: git-branch testsuite update

t3200: git-branch testsuite update

The test expected "git branch --help" to exit successfully, but
built-ins spawn "man" when given --help, and when the test is
run, manpages may not be installed yet and "man" can legally
exit non-zero in such a case.

Also the new implementation logs "Created from master", instead
of "Created from HEAD" in the reflog, which makes a lot more
sense, so adjust the test to match that.

Signed-off-by: Junio C Hamano <redacted>