Infinite recursion for VCPKG in nested pmm projects

[perara]

First of all, this is an excellent manager for easing up the setup time for new projects. Thanks a million!
As i've continued on using this, I've encounted a bug for when I have two dependencies that uses PMM.
The first library executes fine, while the second library gets the following error:

CMake Error at /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:722 (set):
  Maximum recursion depth of 1000 exceeded
Call Stack (most recent call first):
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)
  /home/per/.local/share/pmm/2.0.0/vcpkg-2022.03.10/scripts/buildsystems/vcpkg.cmake:800 (_find_package)

I've tracked this down to the following line: https://github.com/vector-of-bool/pmm/blob/develop/pmm/vcpkg.cmake#L265
I've tried to remove the line, which seemingly fixes it. And also, removed the PARENT_SCOPE flag works.
However, I have no idea on what this is actually doing, so I dont dare to propose this as an fix.

Is this possibly something you could provide a fix for?

Thanks!

[perara]

macro(pmm)
    unset(_PMM_INCLUDE)
    _pmm_project_fn(${ARGV})
    foreach(inc IN LISTS _PMM_INCLUDE)
        if(NOT DEFINED VCPKG_INSTALLED_DIR)
            include(${inc})
        endif()


    endforeach()
endmacro()

Wrapped in a check if VCPKG was already defined before including the vcpkg.cmake. Probably shitty way of doing this, but it did work...