Python warnings

[macosforgebot]

douglm@… originally submitted this as ticket:564

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Seeing messages like this:

----- Running Tests from "scripts/tests/CalDAV/sharing-peruser-data.xml"... ----- 
...
    Test Suite: Different freebusy                            

/home/douglm/drop2/calendar/apple/CalDAVTester-dist/verifiers/propfindItems.py:152: FutureWarning: The behavior of this method will change in future versions.  Use specific 'len(elem)' or 'elem is not None' test instead.
  if not prop:
        Test: 1                                              [OK] 

/home/douglm/drop2/calendar/apple/CalDAVTester-dist/verifiers/postFreeBusy.py:47: FutureWarning: This search is broken in 1.3 and earlier, and will be fixed in a future version.  If you rely on the current behaviour, change it to './{urn:ietf:params:xml:ns:caldav}response/{urn:ietf:params:xml:ns:caldav}calendar-data'
  for calendar in tree.findall("/{urn:ietf:params:xml:ns:caldav}response/{urn:ietf:params:xml:ns:caldav}calendar-data"):
        Test: 2                                              [FAILED] 

[macosforgebot]

@wsanchez originally submitted this as comment:4:⁠ticket:564

• Priority changed from 5: Not set to 3: Important
• Milestone set to Later
• Description modified