Accept NotFoundErrors

• Your vdirsyncer version: vdirsyncer, version 0.16.7
• If applicable, which server software (and which version) you're using: Apple Calendar Server
• Your Python version: Python 3.6.5
• Your operating system: MacOS 10.13.6

Hi there,

I am trying to utilize vdirsyncer to one-way sync some calendars from Apple Calendar Server into a singlefile ics. Unfortunately, it seems there are some broken URLs/Files reported by the server. I would like to accept these errors and just skip over them, but unfortunately vdirsyncer raises an exception and quits:

error: Unknown error occured for username/calendar: /calendars/__uids__/181DB98E-F898-4643-B5A9-E7DBA477B001/calendar/https:%2Fwww.xing.com%2Fevents%2Fgrowthmarketingsummit-2018-1939105.ics
error: Use `-vdebug` to see the full traceback.
debug:   File "/Users/jan/.venvs/vdirsyncer/lib/python3.6/site-packages/vdirsyncer/cli/tasks.py", line 69, in sync_collection
debug:     partial_sync=pair.partial_sync
debug:   File "/Users/jan/.venvs/vdirsyncer/lib/python3.6/site-packages/vdirsyncer/sync/__init__.py", line 136, in sync
debug:     b_nonempty = b_info.prepare_new_status()
debug:   File "/Users/jan/.venvs/vdirsyncer/lib/python3.6/site-packages/vdirsyncer/sync/__init__.py", line 59, in prepare_new_status
debug:     if prefetch else ()):
debug:   File "/Users/jan/.venvs/vdirsyncer/lib/python3.6/site-packages/vdirsyncer/storage/dav.py", line 507, in get_multi
debug:     raise exceptions.NotFoundError(href)

Is there any way (hidden switch) to change this behaviour?

Thank you & best regards,
Jan

Start with the traceback entry points in vdirsyncer/sync/init.py and vdirsyncer/storage/dav.py, especially get_multi where NotFoundError is raised. Reproduce the one-way sync against the reported broken calendar URL and determine how the requested skip behavior should work; done means the sync continues without quitting on that error.