testimage.bbclass: correctly process SIGTERM

Python's unittest will not propagate exceptions upside
of itself, but rather will just catch and print them.

The working way to make it stop is to send a SIGINT
(e.g. simulate a ctrl-c press), which will make it exit
with a KeyboardInterrupt exception.

This also makes pressing ctrl-c twice from bitbake work
again (previously hanging instances of bitbake and qemu were
left around, and bitbake would no longer start until they
were killed manually).

(From OE-Core rev: 72a19f5f0f4bc4472d13b29e46a5c1673977e37a)

Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/testimage.bbclass

@@ -204,7 +204,7 @@ def testimage_main(d):
         """
         Catch SIGTERM from worker in order to stop qemu.
         """
-        raise RuntimeError
+        os.kill(os.getpid(), signal.SIGINT)
 
     testimage_sanity(d)
 
@@ -360,9 +360,9 @@ def testimage_main(d):
         # or if the worker send us a SIGTERM
         tc.target.start(params=d.getVar("TEST_QEMUPARAMS"), runqemuparams=d.getVar("TEST_RUNQEMUPARAMS"))
         results = tc.runTests()
-    except (RuntimeError, BlockingIOError) as err:
-        if isinstance(err, RuntimeError):
-            bb.error('testimage received SIGTERM, shutting down...')
+    except (KeyboardInterrupt, BlockingIOError) as err:
+        if isinstance(err, KeyboardInterrupt):
+            bb.error('testimage interrupted, shutting down...')
         else:
             bb.error('runqemu failed, shutting down...')
         if results: