Hi Dow,
The reason for this error is that we changed the upstream url for the pybind submodule. This is necessary to apply patches to pybind11 which are not (yet) upstream. This update is not done automatically with 'git pull', so you have to do:
Code:
git submodule update --init --recursive
git submodule sync --recursive
git submodule update --init --recursive
The first update will fetch the latest Netgen, but fails at updating pybind11 inside Netgen. 'submodule sync' will update the upstream urls of all submodules (including pybind11). Afterwards the second update checks out the correct version.
Note that you have to do this only once (we will update the documentation). Checking out the latest version from scratch also works around this as you experienced.
Best,
Matthias