[Duplicity-talk] TypeError when running duplicity in Cron

[Nertskull]

I'm not sure this is a duplicity or cron or python issue.

But when I run duplicity on the command line, I get no errors.

But when I run as part of a cronjob, I get this error

  File "/usr/bin/duplicity", line 1532, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1526, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1380, in main
    do_backup(action)
  File "/usr/bin/duplicity", line 1405, in do_backup
    globals.archive_dir).set_values()
TypeError: __init__() takes exactly 4 arguments (3 given)

I run the cronjob using

01 01 * * * /usr/bin/python2.7 /path/to_my/duplicity-script

The script just sets things like which folder and volume size etc.  And
then uses subprocess.call to run duplicity with the correct settings
from the variables in the script.

I'm on Ubuntu 16.04.4 and this is a brand new install.  I was running
this same script on 12.04 and it was working with no issues.

I'm running duplicity version 0.7.17. I installed it using apt-get.

I searched around and found one thread here:

https://askubuntu.com/questions/1000561/deja-dup-init-takes-exactly-4-arguments-3-given?rq=1

But that just seems to suggest that that person updated python modules
weirdly, and installed duplicity through pip.  I have done nothing like
that.  I don't even have pip installed.  Everything is a fresh install
on 16.04.4.

Like I said, it all works when running manually on the command line.  So
I'm not sure its just cron is doing something strange.  But I thought
asking her first would get me pointed in the right direction.

Thanks
-Dan