When called (indirectly) from `gnus-summary-refer-article',
`gnus-request-head' forwards the current group name, rather than the
group where the message will eventually be found, to the backend
`request-head' function.  This can result in bogus group information in
the registry.  For example, I did a gnus-summary-refer-article from 
the group
"nndoc+87lii2ql3x.fsf@lifelogs.com-ephemeral:87lii2ql3x.fsf@lifelogs.com"
and the registry ended up containing
"nntp+Gmane:87lii2ql3x.fsf@lifelogs.com" as the group name when it
should have been "nntp+Gmane:gmane.emacs.devel".

The enclosed patch addresses this problem.