I changed my environment so that nnml is my primary select method.
This has made a bad interaction between gnus-message-archive-group and
gnus-inews-mark-as-read.

My gnus-message-archive-group consists of (MATCH . GROUP) pairs.  The
interpretation of the GROUP in the absence of a method prefix assumes
that nnarchive will be used, but I want to Gcc right into my nnml
groups, which don't normally have a prefix because they're primary
method groups.  Nonetheless, I can put an "nnml:" prefix on them
anyway, so the storing of articles works as I intended.

However, because of the slight difference in the perception of the
method (implicit method normally, with an exceptional case to avoid
nnarchive interpretation in g-m-a-g), the call to
gnus-group-mark-article-read fails to achieve the marking-as-read
result desired.

I would like to make the following small change in order to get around
this problem, but I'm not sure it won't break something else in the
(probably much more typical) case where the mail backend used for Gcc
is a secondary method.  What's needed is to ensure that, ultimately,
the group is referred to in its most "natural" way, which is to say,
with the implicit method of primary groups.

Could this be reviewed and applied if it's safe?  If it's not safe, is
there an alternative solution?