zephyr_mirror: Fix insecure temporary file for log.

This is probably a lot more annoying to use, in that e.g. there are
separate log files for the two directions of the mirror, but we
haven't used these logs for much, so whatever.

(imported from commit d3bc407d90099214d242526c01cd3d3cd9d9d9bd)

bots/zephyr_mirror_backend.py

@@ -35,6 +35,7 @@ import signal
 import logging
 import hashlib
 import unicodedata
+import tempfile
 
 DEFAULT_SITE = "https://humbughq.com"
 
@@ -711,7 +712,12 @@ def configure_logger(direction_name):
         else:
             log_file = "/home/humbug/mirror-log"
     else:
-        log_file = "/tmp/humbug-log." + options.user
+        f = tempfile.NamedTemporaryFile(prefix="humbug-log.%s." % (options.user,),
+                                        delete=False)
+        log_file = f.name
+        # Close the file descriptor, since the logging system will
+        # reopen it anyway.
+        f.close()
     logger = logging.getLogger(__name__)
     log_format = "%(asctime)s " + direction_name + ": %(message)s"
     formatter = logging.Formatter(log_format)