bitbake: parse: Ensure any existing siggen is closed down first

We're still seeing issues with unclosed asyncio event loops. At the
init site, make sure any existing one is closed first to try and avoid
this.

(Bitbake rev: 78dee3c03c75a27531fcff26f9298fce2519bdde)

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

bitbake/lib/bb/parse/__init__.py

@@ -113,6 +113,8 @@ def init(fn, data):
             return h['init'](data)
 
 def init_parser(d):
+    if hasattr(bb.parse, "siggen"):
+        bb.parse.siggen.exit()
     bb.parse.siggen = bb.siggen.init(d)
 
 def resolve_file(fn, d):