File rdiff-backup-dont-pick-empty-sessions.diff of Package rdiff-backup

Subject: Don't pick empty sessions
From: Hans-Peter Jansen <hpj@urpla.net>

Without this patch, rdiff-backup will also take empty sessions
(in other words: sessions without any diffs/changes) for operations
like --remove-older-than xB into account, which defeats the purpose
of limiting the number of backups in the first place. In fact, for 
being asked to keep the last 20 backups, it has removed _all_ usable
backups for me as those changes were done a while back..

Since restore selection is not limited to an exact time argument,
this change doesn't result in additional restore issues. Having said
this, be careful in providing the restore timestamp: e.g. supplying 
the wrong year will happily apply all intermediate diffs after that
date (been there, done that, waited 36 hours :| ).. The good news is:
it finally succeeded, and the VM was still usable.

Index: b/rdiff_backup/restore.py
===================================================================
--- a/rdiff_backup/restore.py
+++ b/rdiff_backup/restore.py
@@ -148,8 +148,6 @@ class MirrorStruct:
 		else: d = {cls._mirror_time: None}
 		if not rp or not rp.index: rp = Globals.rbdir.append("increments")
 		for inc in get_inclist(rp): d[inc.getinctime()] = None
-		for inc in get_inclist(Globals.rbdir.append("mirror_metadata")):
-			d[inc.getinctime()] = None
 		return_list = d.keys()
 		return_list.sort()
 		return return_list