EDIT: I just found that in this wiki under <http://ikiwiki.info/bugs/done/> the entry "mailto: links not properly generated in rss/atom feeds" also doesn't have a hyperlink - at least it's not a problem with my config only ;-)
[[madduck]]: I traced this down to `htmlscrubber`. If disabled, it works. If enabled, then `$safe_url_regexp` determines the URL unsafe because of the colon and hence removes the `src` attribute.
+
+Digging into this, I find that [[rfc 3986]] pretty much discourages colons in
+filenames:
+
+> A path segment that contains a colon character (e.g., "this:that") cannot be
+> used as the first segment of a relative-path reference, as it would be
+> mistaken for a scheme name. Such a segment must be preceded by
+> a dot-segment (e.g., "./this:that") to make a relative- path reference.
+
+on the other hand, with `usedirs`, any link to another page will be prepended
+by `../` anyway, so that makes them okay again.
+
+The solution still seems not to use colons.
+
+In any case, `htmlscrubber` should get a new regexp, courtesy of dato: `[^:]+($|\/)`. I have tested and verified this.