/etc/X11/Xresources no longer loaded, error in patch

After upgrading from 21.04 to 21.10, my /etc/X11/Xresources/ directory no longer loads on login.

Looking at the sources, I think this can be traced to:
 - Switching from a custom Xsession file to the upstream Xsession file in 3.38.0-1ubuntu1, combined with
 - An oversight in `debian/patches/ubuntu/xresources_is_a_dir.patch`

Looking at [that patch](https://salsa.debian.org/gnome-team/gdm/-/blob/ubuntu/master/debian/patches/ubuntu/xresources_is_a_dir.patch), it has:

```diff
--- a/data/Xsession.in
+++ b/data/Xsession.in
@@ -122,6 +122,13 @@ fi

 if [ -f "$sysresources" ]; then
     xrdb -nocpp -merge "$sysresources"
+elif [ -d "$sysresources" ]; then
+ # directory of Xresources files on Debian/Ubuntu
+ for i in `ls "$sysresources"` ; do
+ if [ -r "$sysresources/$i" -a -f "$sysresources/$i" ] && expr "$i" : '^[[:alnum:]_-]\+$' > /dev/null; then
+ xrdb -nocpp -merge "$sysresources/$i"
+ fi
+ done
 fi

 if [ -f "$userresources" ]; then
```

However, looking a few lines further up in [the original Xsession.in file](https://salsa.debian.org/gnome-team/gdm/-/blob/ubuntu/master/data/Xsession.in#L97), I see:

```sh
if [ -f /etc/X11/Xresources ]; then
    sysresources=/etc/X11/Xresources
else
    sysresources=/usr/etc/X11/Xresources
fi
```

In other words, if `/etc/X11/Xresources` is a directory, the `sysresources` variable is never set correctly, so the patch should also modify this part of the script.

I have observed this broken behavior on version 41~rc-0ubuntu2, but looking at the ubuntu/master branch (as linked above), it still seems broken there.

I'm currently testing this patch:

```diff
--- Xsession.orig 2021-12-27 22:05:09.038863375 +0100
+++ Xsession 2021-12-27 22:05:33.143057433 +0100
@@ -111,7 +111,7 @@
 usermodmap="$HOME/.Xmodmap"
 userxkbmap="$HOME/.Xkbmap"

-if [ -f /etc/X11/Xresources ]; then
+if [ -e /etc/X11/Xresources ]; then
     sysresources=/etc/X11/Xresources
 else
     sysresources=/usr/etc/X11/Xresources
```

I don't know if it works yet, since I need to log out for that, and close my browser, so need to submit this report first ;-)

```
$ lsb_release -rd
Description: Ubuntu 21.10
Release: 21.10
$ apt-cache policy gdm3
gdm3:
  Installed: 41~rc-0ubuntu2
  Candidate: 41~rc-0ubuntu2
  Version table:
 *** 41~rc-0ubuntu2 500
        500 http://nl.archive.ubuntu.com/ubuntu impish/main amd64 Packages
        100 /var/lib/dpkg/status
```