OS X 10.11.5, Python 3.5.1 After building as usual.
$ make deploy
/Applications/Xcode.app/Contents/Developer/usr/bin/make -C src qt/bitcoin-qt
/usr/local/bin/python3 ./contrib/macdeploy/macdeployqtplus Bitcoin-Qt.app -add-qt-tr da,de,es,hu,ru,uk,zh_CN,zh_TW -translations-dir= -dmg -fancy ./contrib/macdeploy/fancy.plist -verbose 2 -volname Bitcoin-Core
Error: Could not find background picture at "background.tiff" or "./contrib/macdeploy/background.tiff"
make: *** [Bitcoin-Core.dmg] Error 1
The instructions in macdeploy/README.md might also need updating.