stgit.el: Improve how "t h" mode finds old commits

Use 'git log -<N>' to list historical commits. This avoids showing
more than stgit-committed-count patches (for merges) and does not
cause an error when running out of history.

Signed-off-by: Gustav Hållberg <gustav@gmail.com>
Signed-off-by: David Kågedal <davidk@lysator.liu.se>
1 file changed