Last modified: 2011-04-14 15:13:24 UTC
Tidy replaces tabs with spaces and per documentation http://tidy.sourceforge.net/docs/quickref.html#tab-size it never outputs tabs. However it passes through 	 entity. Thus all tabs in wikitext source between <pre></pre> and <source></source> should be replaced by the entity before passing to Tidy.
We could do str_replace from literal tab to 	 and back in the wrappers around tidy calls. This would transform anything that was already using the numeric entity to a literal tab, but I think our Sanitizer would already do this, and it should be harmless.
Fixed in r42257.
r42257 has been reverted. Reopening.
Specifically because the fix caused other, more severe bugs. The real solution here is to get rid of Tidy.