Rosdep not detecting that pyqt5 is there, despite skip-keys

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I am trying to install ROS on MacOS, following the (unofficial) instructions. I've hit this snag. I am seeing that pyqt5 is a dependency, I know that it is installed, so I place a series of relevant skip-keys. Still rosdep is giving an error. Can someone see what I am doing wrong? Thanks!

bash-3.2$ rosdep install --from-paths src --ignore-src --rosdistro kinetic -y --skip-keys="libqt5-core libqt5-gui libqt5-opengl libqt5-opengl-dev libqt5-widgets qt5-qmake qtbase5-dev python-qt5-bindings python-qt5-bindings-glpython-qt5-bindings-webkit pyqt5"
executing command [brew install pyqt5]
Warning: pyqt 5.9_1 is already installed
ERROR: the following rosdeps failed to install
  homebrew: Failed to detect successful installation of [pyqt5]