folks-0.15.8 tarball does not match tag
wget https://download.gnome.org/sources/folks/0.15/folks-0.15.8.tar.xz
tar xf folks-0.15.8.tar.xz
grep include folks-0.15.8/backends/dummy/lib/meson.build
is missing https://gitlab.gnome.org/GNOME/folks/-/blob/0.15.8/backends/dummy/lib/meson.build?ref_type=tags#L26 for a fix that is included on the tag.