pmbootstrap install fails for phosh on stable

On v20.05, when phosh is selected:

$ pmbootstrap --details-to-stdout install
...
ERROR: unsatisfiable constraints:
  mesa-git-glapi-0_git20200323-r0:
    breaks: mesa-dev-20.0.7-r0[mesa-glapi=20.0.7-r0]
    satisfies: mesa-git-dri-gallium-0_git20200323-r0[mesa-git-glapi]
               mesa-git-dri-gallium-0_git20200323-r0[so:libglapi.so.0]
               .pmbootstrap-20201022.183805[mesa-git-glapi]
               .pmbootstrap-20201022.183805[mesa-glapi]
               mesa-git-gl-0_git20200323-r0[so:libglapi.so.0]
               mesa-git-gles-0_git20200323-r0[so:libglapi.so.0]
               mesa-git-egl-0_git20200323-r0[so:libglapi.so.0]
               mesa-git-osmesa-0_git20200323-r0[so:libglapi.so.0]
...

This is a regression from 2cbde0da:

• nemo pulls in pc:gtk+-3.0 (which it should not do, I think there should be a nemo-dev package)
• pc:gtk+-3.0 depends on gtk+3.0-dev
• gtk+3.0-dev depends on libepoxy-dev
• libepoxy-dev depends on mesa-dev
• mesa-dev depends on mesa-glapi, which conflicts with mesa-git-glapi

Because of apk-tools#10709, we still have mesa-git in postmarketOS v20.05 instead of mesa. I'll look into finally resolving that one over the next days.