Patches:

- patchwork/utf8: Remove trigger_error() that spammed the error log
- Doctrine: fix error handling for not null columns on some mysql servers https://github.com/doctrine/dbal/pull/2422
- SabreDAV: Make sure that files that are children of directories, are reported as files https://github.com/fruux/sabre-dav/issues/982
- SabreDAV: Don't open the file on HEAD requests https://github.com/sabre-io/dav/pull/1058
- SabreDAV: Properly parse carddav address-data https://github.com/sabre-io/dav/pull/1025
- SabreVObject: Broker: add timezone to CANCEL messages https://github.com/sabre-io/vobject/pull/412
- SabreXML: Fix invalid PHP docs https://github.com/fruux/sabre-xml/pull/128
- SabreXML: Prevent infinite loops for empty props element https://github.com/fruux/sabre-xml/pull/132
- ZipStreamer: Fix zip generation for 7zip https://github.com/McNetic/PHPZipStreamer/pull/39
