vc-comment-search-reverse
vc-comment-search-reverse is an alias for `log-edit-comment-search-backward' in `log-edit.el
'.
(vc-comment-search-reverse STR &optional STRIDE)
This function is obsolete since 22.1;
use `log-edit-comment-search-backward' instead.
Search backwards through comment history for substring match of STR.
If the optional argument STRIDE is present, that is a step-width to use
when going through the comment ring.