Colons are not allowed at the start of urls, because it can be interpreted
as a protocol, and allowing arbitrary protocols can be unsafe
(CVE-2008-0809). However, this check was too restrictive, not allowing
use of eg, "video.ogv?t=0:03:00/0:04:00" to seek to a given place in a
video, or "somecgi?foo=bar:baz" to pass parameters with colons.
It's still not allowed to have a filename with a colon in it (ie
"foo:bar.png") -- to link to such a file, a fully qualified url must be
used.
Since Firefox version 3, it's done aggressive caching of visited pages, and
does not, by default, check if the cached content is still valid when
reloading or revisiting a page. By default, Firefox seems to not re-contact
the web server at all. Compare with eg, Epiphany and Chromium, which appear
to always check, and get back a 304 when the page is unchanged.
This header makes Firefox do the right thing, at least for html files. It
still over-caches if css, javascript, images, etc, are changed.
pagespec_translate may set $@ if it fails to parse a pagespec, but
due to memoization, this is not reliable. If a memoized call is repeated,
and $@ is already set for some other reason previously, it will remain
set through the call to pagespec_translate.
Instead, just check if pagespec_translate returns undef.
Actually, tags can't be made to work with and w/o tagbase, so just make it
assume tagbase is set. Better example anyway.
(It'll be a broken link on ikiwiki.info though.)