Added some cleanup after running bower installs.

- Legacy-Id: 12885

bin/mkrelease

@@ -174,7 +174,7 @@ note "Updating bower assets ..."
 $do ietf/manage.py bower_install
 $do svn commit ietf/externals/static -m "Updated bower-managed static web assets"
 # Get rid of bower-installed files which we don't use:
-$do rm $(svn st ietf/externals/ | grep '^\?' | awk '{print $2}')
+$do rm $(svn st ietf/externals/ | grep '^\?' | awk '{print $2}') || true
 $do rm -rf ietf/externals/static/datatracker/
 
 note "Collecting static files ..."