MAINT-2155: when permitting missing old logfile, check for ENOENT

instead of errno.EEXIST. Sigh.

indra/viewer_components/updater/scripts/darwin/update_install.py

@@ -162,7 +162,7 @@ def fail(message):
             os.rename(logname, logname + ".old")
         except OSError, err:
             # Nonexistence is okay. Anything else, not so much.
-            if err.errno != errno.EEXIST:
+            if err.errno != errno.ENOENT:
                 raise
 
         # Open new updater.log.