document file: undo the clean stop's mark before deciding the actor

At start, a node on a document file appends an Opened record before it
writes anything, so that a Closed record before it no longer says the
file holds every change of the actor it names. It does so now before
deciding which actor to write as, and DocumentFile::open says whether it
could: where the append fails (the disk full, permissions), the file
still ends with Closed, and later appends likely fail too. A crash, or a
clean stop whose last append failed (close then sees the file behind and
writes no mark), would leave that Closed standing for a run the file
never got. So with --keep-actor, the node writes on as the actor of
before only where the file was marked as opened; else it writes as a
fresh actor and warns.

0 files changed, 0 insertions, 0 deletions