dispatch: ensure SIGINT triggers KeyboardInterrupt

Summary:
It seems OSX python2 has SIGINT handler set to SIG_IGN by default when running
inside tests. Detect that and reset SIGINT handler to raise KeyboardInterrupt.

This fixes test-ctrl-c.t on OSX.

As we're here, improve test-ctrl-c.t so it checks a bit more things and run
quicker.

Reviewed By: DurhamG

Differential Revision: D23853455

fbshipit-source-id: 05c47650bc80f9880f724828d307c32786265e2c

eden/scm/edenscm/mercurial/dispatch.py

@@ -540,6 +540,11 @@ def _runcatch(req):
                 util.signal(num, catchterm)
     except ValueError:
         pass  # happens if called in a thread
+    # In some cases, SIGINT handler is set to SIG_IGN on OSX.
+    # Reset it to raise KeyboardInterrupt.
+    sigint = getattr(signal, "SIGINT", None)
+    if sigint is not None and util.getsignal(sigint) == signal.SIG_IGN:
+        util.signal(sigint, signal.default_int_handler)
 
     realcmd = None
     try:

eden/scm/tests/test-ctrl-c.t

@@ -17,12 +17,21 @@
   >         time.sleep(1)
   > pid = int(open("pid").read())
   > os.kill(pid, signal.SIGINT)
-  > time.sleep(10)
+  > try:
+  >     for _ in range(30):
+  >         os.kill(pid, 0)  # raise if pid no loner exists
+  >         time.sleep(1)
+  > except Exception:
+  >     pass
   > EOF
 
   $ hg debugpython -- interrupt.py
 
-Should have "interrupted!":
+Should have "interrupted!" printed by dispatch.py:
 
   $ cat err
   interrupted!
+
+Should not have "exited" printed by "echo exited" because non-zero exit code:
+
+  $ cat out