gh-138944: Fix SyntaxError message for invalid syntax following valid import-as statement (#138945)

Lib/test/test_syntax.py

@@ -2163,6 +2163,25 @@
 Traceback (most recent call last):
 SyntaxError: cannot use subscript as import target
 
+# Check that we don't raise a "cannot use name as import target" error
+# if there is an error in an unrelated statement after ';'
+
+>>> import a as b; None = 1
+Traceback (most recent call last):
+SyntaxError: cannot assign to None
+
+>>> import a, b as c; d = 1; None = 1
+Traceback (most recent call last):
+SyntaxError: cannot assign to None
+
+>>> from a import b as c; None = 1
+Traceback (most recent call last):
+SyntaxError: cannot assign to None
+
+>>> from a import b, c as d; e = 1; None = 1
+Traceback (most recent call last):
+SyntaxError: cannot assign to None
+
 # Check that we dont raise the "trailing comma" error if there is more
 # input to the left of the valid part that we parsed.