siggen.py: Include list of variables in hashes

Ensure that the list of dependencies is included in the hash
as well as their contents

Prior to this, adding or removing dependencies with values
of "None" would not change the hash, despite diffsigs reporting
this difference.

(Bitbake rev: 727ca945177ce9bd44515cf611e3e95a09466d98)

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

bitbake/lib/bb/siggen.py

@@ -101,6 +101,7 @@ class SignatureGeneratorBasic(SignatureGenerator):
             alldeps = seen - self.basewhitelist
 
             for dep in sorted(alldeps):
+                data = data + dep
                 if dep in lookupcache:
                     var = lookupcache[dep]
                 else: