assert len(chain_list) == 2 AssertionError

[Erik Hetzner]

I am getting this error in one of my backups (https://bugs.launchpad.net/duplicity/+bug/703142)

duplicity: 0.6.17
python: 2.7
OS distro: Ubuntu 11.10
Target FS: s3

[Erik Hetzner (egh)]

Do you need more information for this? Or perhaps there is a workaround? Many thanks!

[mithro (mithro)]

I think this bug is related to #927280. The following patch should fix it in a very hacky way:
$ diff -u /usr/lib/python2.7/dist-packages/duplicity/collections.py.orig /usr/lib/python2.7/dist-packages/duplicity/collections.py
--- /usr/lib/python2.7/dist-packages/duplicity/collections.py.orig 2012-09-24 11:56:36.058567276 +1000
+++ /usr/lib/python2.7/dist-packages/duplicity/collections.py 2012-09-24 11:56:16.558738678 +1000
@@ -930,6 +930,11 @@
             if len(chain_list) == 1:
                 sorted_chain_list.append(chain_list[0])
             else:
+ while len(chain_list) > 2:
+ assert len(chain_list[0].get_filenames()) == 1
+ assert len(chain_list[2].get_filenames()) == 1
+ del chain_list[0]
+ del chain_list[2]
                 assert len(chain_list) == 2
                 if chain_list[0].backend: # is remote, goes first
                     sorted_chain_list.append(chain_list[0])

[Erik Hetzner (egh)]

I no longer have the backup data which created this error. Thanks for the comment! Closing.