bundle: Accept prerequisites without commit messages
While explicitly stating that the commit message in a prerequisite
line is optional, we required all lines with 40 or more characters
to contain a space after the object name, bailing out if a line
consisted of an object name only. This was to allow bundling a
history to a commit without an message, but the code forgot that it
already called rtrim() to remove that whitespace.
As a workaround, only check for SP when the line has more than 40
characters.
Signed-off-by: Lukas Fleischer <git@cryptocrack.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>