The previous pattern, `*.{mdwn,html}`, would expand to
`HACKING.mdwn *.html` due to `HACKING.mdwn` existing in the Git root
these days, leading to all .mdwn files in the wiki would be ignored.

Fix-committed: #14673

Fix-committed: #12705

Fix-committed: #14623

Fix-committed: #14612

Merge remote-tracking branch 'origin/feature/12034-improve-ux-of-nautilus-in-root-terminal' into devel

Fix-committed: #12034

Fix-committed: #14655

We want at least the Root Terminal to have our /usr/local/{bin,sbin}
scripts *and* overrides in its PATH. Before #12738, when the Root
Terminal was started with gksu instead of pkexec, it inherited
amnesia's PATH, but that is not the case any more.

In particular, now our /usr/local/sbin/nautilus override will be
active in the Root Terminal, which was the point of that override.

Refs: #12034, #12738

Refs: #14612

* It can now handle Array return types.
* It has the `return_shellcommand` flag, which, when set, returns the
  RemoteShellCommand object instead of trying to interpret the return
  value. This is especially useful when `dbus-send` is expected to
  fail.

We actually depend on it for some tests.

Refs: #14612

Fix-committed: #13440

Fix-committed: #13442

Mary Meeker is the author of the "Kleiner Perkins: 2017 Internet trends" report
so I think these two bullet points actually refer to the same document.

Test suite: use 7200 MiB virtual USB drives for snapshots as well when we really mean 8 GiB (refs: #12707).

Fixup on commit c867dd3d.

"." is a regexp special char. We mean "." literally so it ought to be escaped.

Wrong:

 $ echo 'user_pref("extensionsXenigmailYconfiguredVersion",' \
   | sed --regexp-extended \
        '/^(user_)?pref\("extensions.enigmail.configuredVersion",/d'

Right:

 $ echo 'user_pref("extensionsXenigmailYconfiguredVersion",' \
   | sed --regexp-extended \
        '/^(user_)?pref\("extensions\.enigmail\.configuredVersion",/d'
 user_pref("extensionsXenigmailYconfiguredVersion",

Fix-committed: #8917

Fix-committed: #12436, #12707

Apparently I forgot to adapt this scenario when fixing the others.

This just feels like better organization!