If the repo is on a mounted folder that doesn't support chmod (like
SMB), it was causing an "operation not supported" error when trying to
chmod 666 a file before deleting it.
But it isn't generally needed before deleting a file (the folder
permissions matter there, not the file permissions). So, just drop it.
Apparently SMB/CIFS on Linux/macOS returns somewhat random errnos when
trying to sync a windows share which does not support calling fsync for
a directory.
