; Fix erc--channel-modes test on graphical displays

; Fix erc--channel-modes test on graphical displays

* lisp/erc/erc-fill.el (erc-fill--wrap-insert-merged-post): Use
correct variable.
* test/lisp/erc/erc-scenarios-display-message.el: Mute unrelated noisy
test.
* test/lisp/erc/erc-tests.el (erc--channel-modes): Bail out following
first group of assertions when running on a graphical display.
(erc--channel-modes/graphic-p): New test asserting different values
for graphical terminals.  Note that this too is tagged as :unstable.
See also: d2ce30afdd2 "; Mark test for erc--update-channel-modes as
:unstable".