Fix flake8-run.sh to return non-zero on failure.

Author: gsnedders

flake8-run.sh

@@ -7,5 +7,8 @@ fi
 
 if [[ $FLAKE == "true" ]]; then
   find html5lib/ -name '*.py' -and -not -name 'constants.py' -print0 | xargs -0 flake8 --ignore=E501
+  flake1=$?
   flake8 --max-line-length=99 --ignore=E126 html5lib/constants.py
+  flake2=$?
+  exit $[$flake1 || $flake2]
 fi