apport-bug: Add /snap/bin to PATH for Firefox snap

[bdrung]

On LXQt apport-bug is unable to open the Firefox snap at the very end of the process:

$ env -i apport-bug apport
[...]
Choices:
  1: Launch a browser now
  C: Cancel
Please choose (1/C): 1
/usr/bin/xdg-open: 882: firefox: not found
/usr/bin/xdg-open: 882: firefox: not found
xdg-open: no method available for opening 'https://bugs.launchpad.net/ubuntu/+source/apport/+filebug/d7ffa3e0-d46d-11ec-a167-40a8f03099c8?'

The Firefox snap provides /snap/bin/firefox. apport-bug sets the environment variable PATH, but does not include /snap/bin:

$ PATH=/usr/sbin:/usr/bin:/sbin:/bin xdg-open https://ubuntu.com
/usr/bin/xdg-open: 882: firefox: not found
/usr/bin/xdg-open: 882: firefox: not found
xdg-open: no method available for opening 'https://ubuntu.com'

xdg-open behaves differently depending on the desktop environment. On GMOME xdg-open calls gio open and successfully opens Firefox regardless of PATH, but on LXQt it tries to call firefox directly.

Bug: https://launchpad.net/bugs/1973470

[schopin-pro]

Codewise, LGTM. However, I just tried the following:

schopin@gandalf:~$ export PATH=/usr/bin:/bin
schopin@gandalf:~$ firefox
Command 'firefox' is available in '/snap/bin/firefox'
The command could not be located because '/snap/bin' is not included in the PATH environment variable.
firefox: command not found
schopin@gandalf:~$ xdg-open https://ubuntu.com
schopin@gandalf:~$ update.go:85: cannot change mount namespace according to change mount (/var/lib/snapd/hostfs/usr/share/cups/doc-root /usr/share/cups/doc-root none bind,ro 0 0): cannot create directory "/usr/share/cups/doc-root": permission denied
update.go:85: cannot change mount namespace according to change mount (/var/lib/snapd/hostfs/usr/share/gimp/2.0/help /usr/share/gimp/2.0/help none bind,ro 0 0): cannot create directory "/usr/share/gimp/2.0": permission denied
update.go:85: cannot change mount namespace according to change mount (/var/lib/snapd/hostfs/usr/share/libreoffice/help /usr/share/libreoffice/help none bind,ro 0 0): cannot create directory "/usr/share/libreoffice/help": permission denied
update.go:85: cannot change mount namespace according to change mount (/var/lib/snapd/hostfs/usr/share/xubuntu-docs /usr/share/xubuntu-docs none bind,ro 0 0): cannot open directory "/var/lib": permission denied
Missing chrome or resource URL: resource://gre/modules/UpdateListener.sys.mjs

So xdg-open was perfectly capable of launching Firefox even if it isn't availabe in $PATH. I think we might actually be hitting a bug caused by the deb2snap migration?

I'm spinning up a fresh 22.04 VM to see how things are in a pristine env.

[codecov-commenter]

Codecov Report

Merging #2 (59628c0) into main (a9f9593) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main       #2   +/-   ##
=======================================
  Coverage   79.29%   79.29%           
=======================================
  Files          77       77           
  Lines       17222    17222           
=======================================
+ Hits        13656    13657    +1     
+ Misses       3566     3565    -1     

Impacted Files	Coverage Δ
tests/system/test_ui_gtk.py	97.68% <0.00%> (+0.15%)	⬆️

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[murraybd]

Given that the firefox snap is seeded in multiple flavors it is curious to me that this works in an Ubuntu desktop environment but not for Lubuntu.

[bdrung]

xdg-open detects the desktop environment and behaves different depending on it. I reproduced the failure on LXQt and updated the merge request with more details.

[schopin-pro]

LGTM