irc: don't consume ',' in mirc color code if missing foreground color

[chzchzchz]

"To specify a background color, a foreground color has to be given. So a
^C,8 attribute is not valid and thus ignored."

Chomping the ',' will corrupt some mirc color scenes.

[codecov-io]

Codecov Report

Merging #1623 (d400110) into master (4f606ce) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1623   +/-   ##
=======================================
  Coverage   35.24%   35.24%           
=======================================
  Files         202      202           
  Lines       82680    82681    +1     
=======================================
+ Hits        29137    29138    +1     
  Misses      53543    53543           

Impacted Files	Coverage Δ
src/plugins/irc/irc-color.c	93.26% <100.00%> (+0.01%)	⬆️

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[flashcode]

Hi,

Thanks for the PR.

The new behavior is more strict, is it a problem to evaluate codes even if they are considered as invalid?
This could now break if people relies on the fact that WeeChat properly handles them.

Is there some official specifications for these codes? (as far I know there is not, in which case allowing such code could be OK for me).

[chzchzchz]

Quote is taken from https://www.mirc.com/colors.html which is probably the closest thing to canonical. irssi displays the ',', irccloud eats ',' and does bg update + fg reset, weechat eats ',' and bg update. This change will fix the ascii I scroll that tests whether color handling is broken on peoples' clients.

[ailin-nemui]

Irssi did an investigation about this topic here irssi/irssi#742 (comment)