I think this is due an update. I've chosen to update to the latest
version that has been merged into Melpa.
Unfortunately we now need to hack around it trying to run VCS
commands.
My Emacs configuration with thirty-something leaf packages seems fine
after the rebuild.
All package sets are simultaneously updated to accommodate changes to
package-build. Due to new restrictions in package-build, all packages using
`melpaBuild` must now provide a recipe file, even those packages which are not
included in upstream MELPA.
Building packages requires package-build.el from Melpa, but installing
packages only requires package.el. Packages from ELPA are already built,
so there is no need to involve package-build.el.
When building a package from a Melpa recipe file, get the Emacs package
name from the recipe. Nix is more restrictive about packages names than
Emacs, so the Nix name for a package is sometimes different.
