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

[Ivan Shmakov]

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.

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