* extension.c (eval_ext_lang_from_control_command): Avoid dereferencing

NULL pointer.

	testsuite/
	* gdb.python/python.exp (python not supported): Verify multi-line
	python command issues an error.

gdb/testsuite/gdb.python/python.exp

@@ -41,6 +41,13 @@ gdb_test_multiple "python print (23)" "verify python support" {
       gdb_test "source $srcdir/$subdir/source2.py" \
 	  "Error in sourced command file:.*" \
 	  "source source2.py when python disabled"
+
+      # Verify multi-line python commands cause an error.
+      gdb_py_test_multiple "multi-line python command" \
+	  "python" "" \
+	  "print (23)" "" \
+	  "end" "not supported.*"
+
       return -1
     }
     -re "$gdb_prompt $"	{}