fast-import: Document the effect of "merge" with no "from" in a commit
fast-import: Document the effect of "merge" with no "from" in a commit

The fast-import documentation currently does not document the behaviour
of "merge" when there is no "from" in a commit.  This patch adds a
description of what happens: the commit is created with a parent, but
no files.  This behaviour is equivalent to "from" followed by
"filedeleteall".

Signed-off-by: Eyvind Bernhardsen <6c117ee50b6e09ddd63c64736427eae033cac682@orakel.ntnu.no>
Acked-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git