remove error checks already done in set_context()
diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index b997ebc..f4c9655 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -1588,7 +1588,7 @@
 Traceback (most recent call last):
   ...
   File "<doctest test.test_generators.__test__.coroutine[25]>", line 1
-SyntaxError: augmented assignment to yield expression not possible
+SyntaxError: can't assign to yield expression
 
 
 Now check some throw() conditions:
diff --git a/Lib/test/test_genexps.py b/Lib/test/test_genexps.py
index 17ad78a..3d896a5 100644
--- a/Lib/test/test_genexps.py
+++ b/Lib/test/test_genexps.py
@@ -144,7 +144,7 @@
     Traceback (most recent call last):
        ...
       File "<doctest test.test_genexps.__test__.doctests[41]>", line 1
-    SyntaxError: augmented assignment to generator expression not possible
+    SyntaxError: can't assign to generator expression
 
 
 ########### Tests borrowed from or inspired by test_generators.py ############
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 896ee81..c1027b1 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -248,12 +248,12 @@
 SyntaxError: keyword can't be an expression
 
 
-From ast_for_expr_stmt():
+More set_context():
 
 >>> (x for x in x) += 1
 Traceback (most recent call last):
   File "<doctest test.test_syntax[31]>", line 1
-SyntaxError: augmented assignment to generator expression not possible
+SyntaxError: can't assign to generator expression
 >>> None += 1
 Traceback (most recent call last):
   File "<doctest test.test_syntax[32]>", line 1
@@ -261,7 +261,7 @@
 >>> f() += 1
 Traceback (most recent call last):
   File "<doctest test.test_syntax[33]>", line 1
-SyntaxError: illegal expression for augmented assignment
+SyntaxError: can't assign to function call
 
 
 Test continue in finally in weird combinations.