Drop unnecessary executable flags

This patch also adds checks for executable files in
pep8 job.

Change-Id: I862ee6c891af05c58ab2aca1178cfd984efb2d3c

tools/find_executables.sh

@@ -0,0 +1,11 @@
+OUTPUT=`find . \( -name .tox -o -name .git \) -prune -o -type f -perm /a=x -print`
+if [ -n "$OUTPUT" ]; then
+    echo "Unexpected executable files are found:"
+    for f in $OUTPUT; do
+        echo $f
+    done
+    echo
+    echo "If you really need to add an executable file, add it to tools/executable_files.txt"
+    exit 1
+fi
+

tox.ini

@@ -14,7 +14,12 @@ commands = /bin/rm -f .testrepository/times.dbm
 
 [testenv:pep8]
 basepython = python3
-commands = flake8
+whitelist_externals =
+  bash
+  find
+commands =
+  flake8
+  bash {toxinidir}/tools/find_executables.sh
 
 [testenv:npm]
 basepython = python3