selftest/context: Avoid tracebacks from tests using multiprocessing

We can see tracebacks where the SIGTERM handler catches things
it shouldn't. Avoid exit(1) unless we're the process that
it was intended for.

[YOCTO #13664]

(From OE-Core rev: d9c62ffac611310efd47ed6397d31dccb72fe868)

(From OE-Core rev: 45b4bd7b4d30d81bdff0d471e8d97c2322ed2f75)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit dba8c1d5ef)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/selftest/context.py

@@ -280,11 +280,15 @@ class OESelftestTestContextExecutor(OETestContextExecutor):
         return rc
 
     def _signal_clean_handler(self, signum, frame):
-        sys.exit(1)
+        if self.ourpid == os.getpid():
+            sys.exit(1)
     
     def run(self, logger, args):
         self._process_args(logger, args)
 
+        # Setup a SIGTERM handler to allow restoration of files like local.conf and bblayers.conf
+        # but don't interfer with other processes
+        self.ourpid = os.getpid()
         signal.signal(signal.SIGTERM, self._signal_clean_handler)
 
         rc = None