Proxy error in erc with multiple clients

* lisp/erc/erc.el (erc-channel-receive-names): Fix errors
generated when multiple IRC clients talk to a single IRC proxy
(bug#19034).

Backport:

(cherry picked from commit 507e98a54d1aa37823c64993d6b59257a82fe8f4)

1 files changed, 5 insertions, 0 deletions

diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 04e99c7b884..2b22bd55ccc 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -4826,6 +4826,11 @@ channel."
                         (_ (error "Unknown prefix char `%S'" ch) voice))
                       'on)))
           (when updatep
+            ;; If we didn't issue the NAMES request (consider two clients
+            ;; talking to an IRC proxy), `erc-channel-begin-receiving-names'
+            ;; will not have been called, so we have to do it here.
+            (unless erc-channel-new-member-names
+              (erc-channel-begin-receiving-names))
             (puthash (erc-downcase name) t
                      erc-channel-new-member-names)
             (erc-update-current-channel-member