The test data was adapted to cope with some bugs:

- An X-ABLabel for an ADR gets generated by Google CardDAV,
  but when sending it back, the connection to ADR gets ignored
  and the X-ABLabel becomes a stand-alone property.
  Reported to Google, bug gets tracked.

- The double \\ at the end of the custom-label6 property gets
  encoded as a single backslash by the Google encoder, in
  contrast to the backslash in the middle of the custom-label5.
  This is a minor bug, not reported.

  The libsynthesis parser then discards the backslash and
  finally the Google parser strips the trailing white space.

- Google swallows one space before the \n in custom-label5.
