Unescaped left brace in regex is deprecated

[eserte]

When running the test suite with newer perls (e.g. 5.23.2) there are some new warnings:

Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^#patch { <-- HERE  width: 90%; }/ at t/filter.t line 355.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^#patch .lines, .info { <-- HERE color:#999;background:#fff;}/ at t/filter.t line 371.
t/filter.t ......... ok
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/#msg dl.meta { <-- HERE  border: 1px #006 solid; background: #369; padding: 6px; color: #fff;
 }/ at t/html.t line 85.
t/html.t ........... ok
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/#patch ins { <-- HERE background:#dfd;text-decoration:none;display:block;padding:0 10px;}/ at t/htmlcolordiff.t line 71.
t/htmlcolordiff.t .. ok

[theory]

Fixed it in fbe542f a while back.