If you `arc which` and have `arc patch Dnnn`'d someone else's revision into your working copy, we say "no matching revision". Other workflows will recognize the revision, e.g. `arc diff`.
Generally, on some workflows we exclude revisions you don't own. This is confusing, and we should avoid it; instead, we should show them but annotate them. e.g.:
D30 blah blah blah (owned by alincoln)
...or similar.