Update util.py
Include exec as a keyword.
exec is no longer a keyword. https://docs.python.org/3/whatsnew/3.0.html#removed-syntax
diff --git a/apitools/gen/util.py b/apitools/gen/util.py
index 2dbf25e..7cf2902 100644
--- a/apitools/gen/util.py
+++ b/apitools/gen/util.py
@@ -93,7 +93,7 @@
name = re.sub('[^_A-Za-z0-9]', '_', name)
if name[0].isdigit():
name = '_%s' % name
- while keyword.iskeyword(name):
+ while keyword.iskeyword(name) or name is 'exec':
name = '%s_' % name
# If we end up with __ as a prefix, we'll run afoul of python
# field renaming, so we manually correct for it.
