parsing of long or multiple lines for a single entry

If a line, for example the entry LOCATION in the synced ics file contains more than 80 characters or is (broken up and then) followed by another line not pertaining to a new entry, then a client error 400 is thrown on syncing. It disappears as soon as the offending line is removed.

• Your vdirsyncer version: 0.16.6
• If applicable, which server software (and which version) you're using
• Your Python version 3.6.5
• Your operating system OpenSUSE 15
• Your config file:

[pair Calendar]
a = "CalendarLocal"
b = "CalendarRemote"
# collections = ["private", "work"]
collections = ["from b"]

# Calendars also have a color property
metadata = ["calendar", "blue"]

# To resolve a conflict the following values are possible:
#   `null` - abort when collisions occur (default)
#   `"a wins"` - assume a's items to be more up-to-date
#   `"b wins"` - assume b's items to be more up-to-date
conflict_resolution = "a wins"

[storage CalendarLocal]
type = "filesystem"
path = "~/.local/share/vdirsyncer/calendars/"
fileext = ".ics"

[storage CalendarRemote]
type = "caldav"
url = "https://spica.t-online.de"
username = "konfekt@t-online.de"
password.fetch = ["command", "pass", "t-online"]

• Use vdirsyncer -vdebug for debug output:

error: Unknown error occured for restCalendar/USER_CALENDAR-MAIN: 400 Client Error:  for url: https://spica.t-online.de/spica-calendar/caldav/principals/konfekt@t-online.de/calendars/USER_CALENDAR-MAIN/120049010000000065340288-ZOOM954798596OCCURRENCE1560614400000.ics
error: Use `-vdebug` to see the full traceback.
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/cli/utils.py", line 74, in handle_cli_error
debug:     raise e
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/sync/__init__.py", line 153, in sync
debug:     partial_sync
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/sync/__init__.py", line 274, in run
debug:     partial_sync)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/sync/__init__.py", line 177, in run
debug:     self._run_impl(a, b)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/sync/__init__.py", line 228, in _run_impl
debug:     self.dest.storage.update(meta.href, self.item, meta.etag)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/storage/base.py", line 15, in inner
debug:     return f(self, *args, **kwargs)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/storage/base.py", line 15, in inner
debug:     return f(self, *args, **kwargs)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/storage/dav.py", line 546, in update
debug:     href, etag = self._put(self._normalize_href(href), item, etag)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/storage/dav.py", line 520, in _put
debug:     headers=headers
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/storage/dav.py", line 390, in request
debug:     return http.request(method, url, session=self._session, **more)
debug:   File "/usr/lib/python3.6/site-packages/vdirsyncer/http.py", line 163, in request
debug:     r.raise_for_status()
debug:   File "/home/konfekt/.local/lib/python3.6/site-packages/requests/models.py", line 935, in raise_for_status

Start with the traceback path in sync/init.py and storage/dav.py, especially update(), _put(), and request(), then reproduce the sync using an ICS entry with a long or folded LOCATION line. Done means the affected entry syncs successfully without the reported HTTP 400 error; the issue does not identify a specific test or implementation file.