Last modified: 2013-07-30 19:38:24 UTC
Bug 51092 added support for $wgAllowExternalImages and $wgAllowExternalImagesFrom. But the PHP parser offers yet another option: $wgEnableImageWhitelist, which reads the whitelist from MediaWiki:External image whitelist Parsoid doesn't support this at the current time.
No plans for fixing this bug. But recording the issue in bugzilla just in case it becomes important someday down the line.
Note that enwiki currently sets $wgEnableImageWhitelist=true; bug 52290 asks that it be turned off.