bug#22789: 25.1.50; In last master build https connections stop working

[Eli Zaretskii]

> From: Alain Schneble <a.s@realize.ch>
> CC: <larsi@gnus.org>, <j_l_domenech@yahoo.com>, <22789@debbugs.gnu.org>
> Date: Sat, 5 Mar 2016 19:27:09 +0100
> 
> I should have written "multiple times" not "many times".  I just had a
> case where for four network processes (get image requests)
> gnutls_try_handshake returned for each of these processes -28
> GNUTLS_E_AGAIN three times in a row, followed by a single -110
> GNUTLS_E_PREMATURE_TERMINATION and then repeatedly by -10
> GNUTLS_E_INVALID_SESSION.

Sounds like we are terminating the connection while the handshake is
still in progress?