commit: pass --no-divider to interpret-trailers

commit: pass --no-divider to interpret-trailers

When git-commit sees any "--trailer" options, it passes the
COMMIT_EDITMSG file through git-interpret-trailers. But it does so
without passing --no-divider, which means that interpret-trailers will
look for a "---" divider to signal the end of the commit message.

That behavior doesn't make any sense in this context; we know we have a
complete and solitary commit message, not something we have to further
parse. And as a result, we'll do the wrong thing if the commit message
contains a "---" marker (which otherwise is not syntactically
significant), inserting any new trailers at the wrong spot.

We can fix this by passing --no-divider. This is the exact situation for
which it was added in 1688c9a489 (interpret-trailers: allow suppressing
"---" divider, 2018-08-22). As noted in the message for that commit, it
just adds the mechanism, and further patches were needed to trigger it
from various callers.  We did that back then in a few spots, like
ffce7f590f (sequencer: ignore "---" divider when parsing trailers,
2018-08-22), but obviously missed this one.

Reported-by: <eric.frederich@siemens.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>