Error when returning Eigen::SparseVector

While returning sparse matrices works out pretty well, returning sparse vectors causes an error.
The exact error message I get is:

...
.../pybind11/include/pybind11/eigen.h:581:32: fatal error: no member named 'makeCompressed' in 'Eigen::SparseVector<double, 0, int>'
const_cast<Type&>(src).makeCompressed();
...

This seems to be due to the fact that Eigen::SparseVector derives from Eigen::SparseCompressedBase instead of
Eigen::SparseBase, such that the method makeCompressed does not exists.

I don't recall having this issue in the past. On the other hand, the last change to the relevant file (EIGEN_DIR/src/SparseCore/SparseVector.h) has been made almost 2 years ago.

Here is a minimal reproducible example:

#include <Eigen/Sparse>
#include <pybind11/eigen.h>

PYBIND11_MODULE(_returnSparseVector, m)
{
	m.def("returnSparse", []() -> Eigen::SparseVector<double> {
		Eigen::SparseVector<double> vec(10);
		return vec;
	} );
}

Compiler: Apple clang version 11.0.3 (clang-1103.0.32.62)
pybind11: latest (git master branch)
Eigen: latest (git master branch)

Reproduce the minimal C++ example using Eigen/Sparse and pybind11/eigen.h, then inspect the conversion code around line 581 and the Eigen::SparseVector inheritance described in the report. Done means returning an Eigen::SparseVector compiles and works without the makeCompressed error, while existing sparse-matrix returns continue to work.