Hunting the culprit package

[Pankaj Jangid <pankaj@codeisgreat.org>]

I am trying to find out which package inside my ~/.emacs.d/elpa is the
culprit. One of the packages is introducing a bug. I know this because
when I move my ~/.emacs.d/elpa directory and launch emacs without any
packages installed then it works fine.

Also, when I install all the packages afresh, then also emacs works fine
i.e. a freshly created ~/.emacs.d/elpa is *not* creating any issue. So
something is wrong in my old ~/.emacs.d/elpa. So I tried to figure out
what is happening in my old ~/.emacs.d/elpa directory.

Before that I restored my old ~/.emacs.d/elpa and upgraded all the
packages to latest. And then compared old an new directories using "diff
-r". Strangely, the diff output is 900+ lines.

My question is that - why there is a difference? I have refreshed all
the packages in old ~/.emacs.d/elpa directory and comparing it with a
freshly created ~/.emacs.d/elpa. And the difference is not in cache
etc. "diff -r" is clearly showing differences in source files. Sample,

--8<---------------cut here---------------start------------->8---
diff -r elpa/dash-20220608.1931/dash-autoloads.el elnew/dash-20220608.1931/dash-autoloads.el
42c42
< (fn &optional ARG)" t nil)
---
> (fn &optional ARG)" t)
66c66
< (fn &optional ARG)" t nil)
---
> (fn &optional ARG)" t)
69c69
< This allows Dash symbols to be looked up with \\[info-lookup-symbol]." t nil)
---
> This allows Dash symbols to be looked up with \\[info-lookup-symbol]." t)

...


diff -r elpa/yaml-mode-20220104.1503/yaml-mode-pkg.el elnew/yaml-mode-20220104.1503/yaml-mode-pkg.el
2c2
< (define-package "yaml-mode" "20220104.1503" "Major mode for editing YAML files" '((emacs "24.1")) :commit "535273d5a1eb76999d20afbcf4d9f056d8ffd2da" :authors '(("Yoshiki Kurihara" . "clouder@gmail.com") ("Marshall T. Vandegrift" . "llasram@gmail.com")) :maintainer '("Vasilij Schneidermann" . "mail@vasilij.de") :keywords '("data" "yaml") :url "https://github.com/yoshiki/yaml-mode")
---
> (define-package "yaml-mode" "20220104.1503" "Major mode for editing YAML files" '((emacs "24.1")) :commit "a79d2a7b9281f8c56f461d717b1ba40fc58e22fd" :authors '(("Yoshiki Kurihara" . "clouder@gmail.com") ("Marshall T. Vandegrift" . "llasram@gmail.com")) :maintainer '("Vasilij Schneidermann" . "mail@vasilij.de") :keywords '("data" "yaml") :url "https://github.com/yoshiki/yaml-mode")
--8<---------------cut here---------------end--------------->8---

Also, if this is not the correct way to approach then how to find which
the old package that was creating the issue. This is in addition to my
earlier question - why there are differences between refreshed upgraded
packages and packages installed from scratch.

All clues will help.

Regards
Pankaj