bug#34910: 27.0.50; Too much matching reentrancy

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Cc: dancol@dancol.org, 34910@debbugs.gnu.org
> Date: Tue, 19 Mar 2019 13:50:00 +0100
> 
> Here is another improvement: there should be no reason to keep the
> regexp busy during the overflow error processing, so release it first.

Looks OK to me.

> By the way, is there any reason why only calls to re_search_2 are made
> with a busy-marked regexp buffer, not calls to re_search? Are the
> latter guaranteed not to be reentrant?

Not sure.  Stefan, any thoughts?