bitbake: utils: Add signal blocking for lock_timeout

We never want to exit whilst holding these locks as it deadlocks all python
threads. Add signal blocking around the lock critical part so a signal
shouldn't cause such an exit.

(Bitbake rev: a097755c671e2b530dea6200a94b39fa9dca246c)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/utils.py

@@ -1882,6 +1882,7 @@ def path_is_descendant(descendant, ancestor):
 @contextmanager
 def lock_timeout(lock):
     try:
+        s = signal.pthread_sigmask(signal.SIG_BLOCK, signal.valid_signals())
         held = lock.acquire(timeout=5*60)
         if not held:
             bb.server.process.serverlog("Couldn't get the lock for 5 mins, timed out, exiting.\n%s" % traceback.format_stack())
@@ -1889,3 +1890,4 @@ def lock_timeout(lock):
         yield held
     finally:
         lock.release()
+        signal.pthread_sigmask(signal.SIG_SETMASK, s)