* nnimap.el (nnimap-decode-group-name, nnimap-encode-group-name):

* nnimap.el (nnimap-decode-group-name, nnimap-encode-group-name):
In-place substitutions for the group name encoding/decoding.
(nnimap-find-minmax-uid, nnimap-possibly-change-group)
(nnimap-retrieve-headers-progress, nnimap-possibly-change-group)
(nnimap-retrieve-headers-progress, nnimap-request-article-part)
(nnimap-update-unseen, nnimap-request-list)
(nnimap-retrieve-groups, nnimap-request-update-info-internal)
(nnimap-request-set-mark, nnimap-split-to-groups)
(nnimap-split-articles, nnimap-request-newgroups)
(nnimap-request-create-group, nnimap-request-accept-article)
(nnimap-request-delete-group, nnimap-request-rename-group)
(nnimap-acl-get, nnimap-acl-edit): Use them.  Replace `mbx' with
`encoded-mbx' for consistency.
(nnimap-close-group): Call `imap-current-mailbox' instead of using the
variable `imap-current-mailbox'.

* gnus-agent.el (gnus-agent-fetch-articles, gnus-agent-fetch-headers)
(gnus-agent-regenerate-group): Use `gnus-agent-decoded-group-name'.