Re: [PATCH] commit-tree: disallow an empty single-parent commit.

Junio C Hamano [off-list ref] writes:

Allow "git-commit-tree v2.6.15^{tree} -p HEAD", instead of
requiring "git-commit-tree `git rev-parse v2.6.15^{tree}` -p
HEAD".  The parent parameter that follows -p uses get_sha1() to
understand the extended notation, and there is little reason not
to allow it for the tree object name parameter.

Also make the check_valid() function simpler.  This function
which predates sha1_object_info() so it had to do things by hand
but there is no reason to read the data just to discard anymore.

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

Looks good to me. The logic at least looks complete.

Eric