Avoid expanding --all when passing arguments to git log.

Avoid expanding --all when passing arguments to git log.
There is no need to expand --all into a list of all revisions as
git log can accept --all as an argument. This avoids any command-line
length limitations caused by expanding --all into a list of all
revision ids.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>