emacs-package updates: No propagation of pname as default to ename for self-declared packages

[periklis]

Issue description

After upgrading to

nixpkgs/pkgs/build-support/emacs/melpa.nix

Line 16 in 0015c34

, ename ? pname

, i get the following error message for self-declared packages like find-file-in-project and pdf-tools:

builder for '/nix/store/k0j7g3n0dn8mfvsa0qckzrqm49h33jbb-emacs-find-file-in-project-3.5.drv' failed with exit code 25
5; last 9 log lines:                                                                                                
  unpacking sources
  unpacking source archive /nix/store/cnlff99n4dq6l3kfrqxil67vcjxgvi38-source
  source root is source
  patching sources
  configuring
  no configure script, doing nothing
  building
  installing
  Opening input file: No such file or directory, /private/tmp/nix-build-emacs-find-file-in-project-3.5.drv-0/packages
/-3.5.tar 

Technical details

nix-shell -p nix-info --run "nix-info -m"                                                                                                                             
 - system: `"x86_64-darwin"`
 - host os: `Darwin 17.6.0, macOS 10.13.5`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Nix) 2.0.4`
 - channels(root): `"nixpkgs-18.03pre116939.d7d774deea"`
 - channels(ptsirakidis): `""`
 - nixpkgs: `/Users/ptsirakidis/projects/ptsirakidis/nix-config/nixpkgs`

cc @ttuegel & @Mic92

[periklis]

Closed by #44060