Exception ''<' not supported between instances of 'RPath' and 'RPath''

Hi,

after upgrading rdiff-backup from 1.2.8 to 2.0 on CentOS 7 I have this 
error:

Previous backup seems to have failed, regressing destination now.
Exception ''<' not supported between instances of 'RPath' and 'RPath'' raised of class '<class 'TypeError'>':
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 390, in error_check_Main
     Main(arglist)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 412, in Main
     take_action(rps)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 348, in take_action
     Backup(rps[0], rps[1])
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 428, in Backup
     backup_final_init(rpout)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 618, in backup_final_init
     checkdest_if_necessary(rpout)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 1127, in checkdest_if_necessary
     dest_rp.conn.regress.Regress(dest_rp)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/regress.py", line 70, in Regress
     for rf in iterate_meta_rfs(mirror_rp, inc_rpath):
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/regress.py", line 214, in iterate_meta_rfs
     collated = rorpiter.Collate2Iters(raw_rfs, yield_metadata())
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/regress.py", line 198, in yield_metadata
     metadata_iter = metadata.ManagerObj.GetAtTime(regress_time)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 611, in GetAtTime
     cur_iter = self.get_meta_at_time(time, restrict_index)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 770, in get_meta_at_time
     for rp in self.relevant_meta_incs(time)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 780, in relevant_meta_incs
     inclist = self.sorted_prefix_inclist(b'mirror_metadata', min_time=time)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 729, in sorted_prefix_inclist
     sortlist.sort()

Traceback (most recent call last):
   File "/bin/rdiff-backup", line 32, in <module>
     rdiff_backup.Main.error_check_Main(sys.argv[1:])
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 390, in error_check_Main
     Main(arglist)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 412, in Main
     take_action(rps)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 348, in take_action
     Backup(rps[0], rps[1])
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 428, in Backup
     backup_final_init(rpout)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 618, in backup_final_init
     checkdest_if_necessary(rpout)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/Main.py", line 1127, in checkdest_if_necessary
     dest_rp.conn.regress.Regress(dest_rp)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/regress.py", line 70, in Regress
     for rf in iterate_meta_rfs(mirror_rp, inc_rpath):
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/regress.py", line 214, in iterate_meta_rfs
     collated = rorpiter.Collate2Iters(raw_rfs, yield_metadata())
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/regress.py", line 198, in yield_metadata
     metadata_iter = metadata.ManagerObj.GetAtTime(regress_time)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 611, in GetAtTime
     cur_iter = self.get_meta_at_time(time, restrict_index)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 770, in get_meta_at_time
     for rp in self.relevant_meta_incs(time)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 780, in relevant_meta_incs
     inclist = self.sorted_prefix_inclist(b'mirror_metadata', min_time=time)
   File "/usr/lib64/python3.6/site-packages/rdiff_backup/metadata.py", line 729, in sorted_prefix_inclist
     sortlist.sort()
TypeError: '<' not supported between instances of 'RPath' and 'RPath'

----

This is fatal because rdiff-backup has ended without any action.

I use command:
rdiff-backup --preserve-numerical-ids --print-statistics /home/ 
/backup/home/
Source is 164569M large, target is 587348M

Now I run backup to new destination /backup/home2 for some time - it 
looks it will do backup without error.

Merac