Previously such files (typically log files) wouldn't be backed up at
all!
The proper behaviour is to backup what we can, and warn the operator
that file is possibly not complete. But it is a warning, not an error.
Closes #689
This code is introduced to watch for issue #529, in which two users
describe that restic failed encoding a time in a node to JSON with the
error message:
panic: json: error calling MarshalJSON for type *restic.Node: json: error calling MarshalJSON for type time.Time: Time.MarshalJSON: year outside of range [0,9999]
The error message now is:
panic: Marshal: json: error calling MarshalJSON for type *restic.Node: node /home/fd0/shared/work/restic/restic/.git/hooks/applypatch-msg.sample has invalid ModTime year -1: -0001-01-02 03:04:05.000000006 +0053 LMT
