bitbake: cooker: Fix siggen recipe cache race issue

We need to reset the cache before the start() call which starts the
parsing processs, tweak the code to ensure this is the case.

(Bitbake rev: 4712d6237df5d2188238294fbdb9f107b068a3a7)

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

bitbake/lib/bb/cooker.py

@@ -2187,12 +2187,11 @@ class CookerParser(object):
         self.num_processes = min(int(self.cfgdata.getVar("BB_NUMBER_PARSE_THREADS") or
                                  multiprocessing.cpu_count()), self.toparse)
 
+        bb.cache.SiggenRecipeInfo.reset()
         self.start()
         self.haveshutdown = False
         self.syncthread = None
 
-        bb.cache.SiggenRecipeInfo.reset()
-
     def start(self):
         self.results = self.load_cached()
         self.processes = []