bug#20471: Emacs ceased to respond to C-g on a tty; SIGINT became blocked?

[Ivan Shmakov <ivan@siamics.net>]

Package: emacs

	After some unfortunate interaction with a process (or perhaps a
	network connection), one of my Emacs instances (built from Git;
	1c7f0cdc4c1f, 2015-04-27 16:59:11 UTC) ceased to respond to C-g
	on a tty.

	Attaching GDB to it shows no signals being delivered on C-g,
	which (AIUI) hints at either SIGINT being blocked /or/ C-g
	“unbound” from the signal via terminal settings.  I’ve copied
	the latter from a terminal used by a properly working Emacs
	instance with the stty(1) invocation below, yet I still see no
	signals via GDB, which leaves the signal mask as the only point
	of failure that I can think of.

$ stty -F /dev/pts/non-working "$(stty -gF /dev/pts/working)" 

	Any suggestion on how do I debug this issue any further?

	TIA.

-- 
FSF associate member #7257  np. Dance of Death — Iron Maiden … B6A0 230E 334A