Glance cache cleaner wrongly deletes cache for non invalid images

The cache cleaner is currently cleaning invalid images like so:

def clean(self, stall_time=None):
        """
        Delete any image files in the invalid directory and any
        files in the incomplete directory that are older than a
        configurable amount of time.
        """
        self.delete_invalid_files()

        if stall_time is None:
            stall_time = CONF.image_cache_stall_time

        now = time.time()
        older_than = now - stall_time
        self.delete_stalled_files(older_than)

def delete_stalled_files(self, older_than):
        """
        Removes any incomplete cache entries older than a
        supplied modified time.

        :param older_than: Files written to on or before this timestemp
                           will be deleted.
        """
        for path in self.get_cache_files(self.incomplete_dir):
            os.unlink(path)
            LOG.info(_("Removed stalled cache file %s"), path)

Although the "older_than" time is passed its not used anywhere, as a result if you run this through a cron, valid images in process for download/getting cached will be deleted from /incomplete since the cleaner does not check for time at all.

Glance api log will complain when this happens in the middle of the fetch:

Fetch finished, moving '/var/lib/glance/image-cache/incomplete/b9b38c90-cf64-4fa9-9e73-73da77e40074' to '/var/lib/glance/image-cache/b9b38c90-cf64-4fa9-9e73-73da77e40074' commit

ERROR glance.image_cache [...] Exception encountered while tee'ing image 'b9b38c90-cf64-4fa9-9e73-73da77e40074' into cache: [Errno 2] No such file or directory. Continuing with response.