This allows cargo metadata to operate on it without adding the source files to the build. (A choice which will save a few rebuilds of the manual) (cherry picked from commit 1779295f3e13cc15f8422d52a3753bb927ac8fa7)
(cherry picked from commit 67616c4a55b9d98d716384ffc07d3b3880dd76e4)
nix_state_create
lookupPath
(cherry picked from commit 6e5a259f60725b632e52d4839e6e3c285d6971d4)
(cherry picked from commit bf1ddd1c9137578b86895577d5b80e0c5771b605)