I have a few files that have been executable before svn adding them. They have the svn:executable property set. Now, a few other files were checked in without the executable
Here is how I set the executable property on all the *.py files in my project that have execute bit set on them. I execute this from the top level directory
for f in `find ./ -name '*.py'`; do echo $f; if [ -x $f ]; then echo $f 'is executable setting svn:executable'; svn propset svn:executable on $f; else echo $f 'is not executable'; fi; done;