siggen.py: Use basehash if no taskhash

The bitbake-runtask doesn't work since there is no taskhash (it worked
in the past, but seems recent changes made it doesn't work again), use
the basehash when there is no taskhash, just like what dump_sigtask
does.

[YOCTO #1229]

(Bitbake rev: b36f2e3803dfc494d5b171759f55faf33708e6f1)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/siggen.py

@@ -223,7 +223,11 @@ class SignatureGeneratorBasicHash(SignatureGeneratorBasic):
             k = fn + "." + taskname[:-9]
         else:
             k = fn + "." + taskname
-        h = self.taskhash[k]
+        if k in self.taskhash:
+            h = self.taskhash[k]
+        else:
+            # If k is not in basehash, then error
+            h = self.basehash[k]
         return ("%s.%s.%s.%s" % (stampbase, taskname, h, extrainfo)).rstrip('.')
 
 def dump_this_task(outfile, d):