This trivial patch makes "git-rev-list" able to handle not being in
the top-level directory.  This magically also makes "git-whatchanged"
do the right thing.

Trivial scripting fix to make sure that "git log" also works.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

When no usable head/tag is specified, git log barfed with
underlying error message from rev-list, which was not helpful.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Instead of getting an incomprehensible error message from git-rev-list.

See the previous commit for explanations.

The "git" script is just shorthand: "git xyz <args>" will just execute
"git-xyz-script <args>", which is useful for people used to the CVS
naming convention. So "git log" will run the new git-log-script, which
is just a wrapper around the new pretty-printing git-rev-list.

Cheesy.