3.0.x: check regex against multiple instances of attribute

[Alan DeKok]

Phil Mayers wrote:
> =~ used to do this i.e. loop over the attributes, but no longer does; I
> think it got lost in the great unlang rewrite.

  It should behave like the other comparison attributes.  So that's
either consistent and correct, or inconsistent and wrong.

> You'll have to foreach over the attribute then regexp-compare against
> "%{Foreach-Variable-X}" - you do need to string-ify it, as it's not a
> real attribute.

  I've tried to figure out how to fix that... it's not obvious.  Maybe
some bizarre internal hacks would do it.

  Alan DeKok.