bitbake: lib: amend code to use proper singleton comparisons where possible

amend the code to handle singleton comparisons properly so it only checks
if they only refer to the same object or not, and not bother
comparing the values.

(Bitbake rev: b809a6812aa15a8a9af97bc382cc4b19571e6bfc)

Signed-off-by: Frazer Clews <frazer.clews@codethink.co.uk>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/ply/yacc.py

@@ -488,7 +488,7 @@ class LRParser:
                     # --! DEBUG
                     return result
 
-            if t == None:
+            if t is None:
 
                 # --! DEBUG
                 debug.error('Error  : %s',
@@ -766,7 +766,7 @@ class LRParser:
                     n = symstack[-1]
                     return getattr(n,"value",None)
 
-            if t == None:
+            if t is None:
 
                 # We have some kind of parsing error here.  To handle
                 # this, we are going to push the current token onto
@@ -1021,7 +1021,7 @@ class LRParser:
                     n = symstack[-1]
                     return getattr(n,"value",None)
 
-            if t == None:
+            if t is None:
 
                 # We have some kind of parsing error here.  To handle
                 # this, we are going to push the current token onto