Immutable files left on exception

[mgorny]

When bedup fails during the process due to exception (maximum recursion depth exceeded / #29) in this case, it leaves files immutable on the fs:

$ lsattr -R |& grep -- --i--
----i----------- ./var/lib/postgresql/9.4/data/global/pg_control
----i----------- ./var/lib/postgresql/9.4/data/global/11882
----i----------- ./var/lib/postgresql/9.4/data/global/12020
----i----------- ./var/lib/postgresql/9.4/data/global/12021
----i----------- ./var/lib/postgresql/9.4/data/global/12022
----i----------- ./var/lib/postgresql/9.4/data/global/12026
[...]

This is quite undesired since it causes most of the applications to fail to work with them, and requires manual cleanup.

[sulaweyo]

I can verify that one as well. Caused by #29 in my case.