URL Rewriter: Unexpected behavior

I tried setting up an advanced rewriting rule to redirect all URLs starting with abc/def to a fixed URL. Based on the forge documentation, I set the From field to

^/abc/def

and the to field to the desired URL www.host.com/xyz.

Using this on the request URL .../abc/def/hgi.html caused a redirection to www.host.com/xyz/hgi.html. Beware: the unmatched, trailing URL segment got appended to the To URL. That was unexpected, as the documentation (as I read it) suggests that this doesn't happen.

Since this is the current behavior, I guess we can't change it, but I suggest that we explicitly document this in order to prevent confusion.
I managed to get my desired behavior by using a From field of

^/abc/def.*$