The Debian packaging of emacs-async is maintained in git, using the
merging workflow described in dgit-maint-merge(7).  There isn't a
patch queue that can be represented as a quilt series.

A detailed breakdown of the changes is available from their canonical
representation - git commits in the packaging repository.  For
example, to see the changes made by the Debian maintainer in the first
upload of upstream version 1.2.3, you could use:

    % git clone https://git.dgit.debian.org/emacs-async
    % cd emacs-async
    % git log --oneline 1.2.3..debian/1.2.3-1 -- . ':!debian'

(If you have dgit, use `dgit clone emacs-async`, rather than plain
`git clone`.)

A single combined diff, containing all the changes, follows.
--- emacs-async-1.9.9.orig/README.md
+++ emacs-async-1.9.9/README.md
@@ -1,9 +1,3 @@
-<p><a href="http://www.gnu.org/licenses/gpl-3.0.txt"><img src="https://img.shields.io/badge/license-GPL_3-green.svg" alt="License GPL 3" /></a>
-<a href="https://elpa.gnu.org/packages/async.html"><img src="https://elpa.gnu.org/packages/async.svg" alt="GNU ELPA" title="" /></a>
-<a href="http://melpa.org/#/async"><img src="http://melpa.org/packages/async-badge.svg" alt="MELPA" title="" /></a>
-<a href="http://stable.melpa.org/#/async"><img src="http://stable.melpa.org/packages/async-badge.svg" alt="MELPA Stable" title="" /></a></p>
-
-
 # emacs-async
 
 `async.el` is a module for doing asynchronous processing in Emacs.
@@ -14,15 +8,6 @@ Some async applications are provided as
 * async-bytecomp
 * async-package
 
-# Install
-
-You can install emacs-async package from MELPA using package.el.
-
-You can also install from sources, in this case you should install
-using make and make install to ensure emacs-async is installed in a
-standard load-path destination where other packages can find it
-easily when compiling.
-
 ## Install dired-async
 
 Add to your `.emacs.el`:
@@ -39,10 +24,6 @@ you can disable this by running the copy
 
 If you don't want to make dired/helm asynchronous disable it with `dired-async-mode`.
 
-### Debian and Ubuntu
-
-Users of Debian 9 or later or Ubuntu 16.04 or later may simply `apt-get install elpa-async`.
-
 ## Authentication and user interaction
 
 Some authentications require user interaction, for example answering to a
