Bug 1629636 removed the FTP registration only on Nightly. We should remove it on beta and release as soon as bug 1691890 has been fixed.

For all channels, this commit:

1. stops registering the ftp protocol handler at install time;
2. actively unregisters the ftp protocol handler at postupdate time;
3. stops unregistering the ftp protocol handler at uninstall time.

The rationale for 3) is that by the time a helper.exe with this
change is in place, the postupdate step has already run and
unregistered the ftp protocol handler.

Central-as-beta simulation try builds are percolating.

• before/without change: https://treeherder.mozilla.org/#/jobs?repo=try&revision=630ec140841edb5cc9c4d9d72c5608f221d8b1d9
• after/with change: https://treeherder.mozilla.org/#/jobs?repo=try&revision=c054627de5c1395f360ec0d5cb07d581d2269e86

For QA:

• Try build Windows x64 installer with this patch
• Try build Windows x64 installer without this patch

These try builds are "central-as-beta" simulations: the branding is all Firefox Nightly, but the flags are all configured for Beta.

There are two things that I tested in this ticket. The test for whether Firefox is registered as an FTP protocol handler is, on Win 10, to go to "Settings > Choose a default app for each protocol" and verify if the correct Firefox is listed as an option for the ftp:// protocol. Be aware that the list needs to be refreshed manually after changes (by going to Settings and entering the section again).

1. First, that a fresh install with this patch does not register Firefox as an FTP protocol handler. To test, install the new version, and verify.

Now, copy out the new uninstall/helper.exe to a temporary location and uninstall the Firefox just installed entirely.

2. Second, test that the post-update step from a fresh install applied to an old install unregisters Firefox as an FTP protocol handler. To run the post-update step: install the old version (without); copy in the updated uninstall/helper.exe from above; then, in the uninstall directory, run helper.exe /PostUpdate.

This should succeed with both elevated and unelevated installers (providing you invoke the helper.exe with Administrator privileges).

Folks, this ticket is ready: patch has r+ and my testing (https://bugzilla.mozilla.org/show_bug.cgi?id=1691951#c3) showed no issues. We can land immediately or block on https://bugzilla.mozilla.org/show_bug.cgi?id=1691890, as :emk suggests.

Unless somebody directs me otherwise, I will only land once https://bugzilla.mozilla.org/show_bug.cgi?id=1691890 has landed.

https://hg.mozilla.org/mozilla-central/rev/7ea6d7472432

I have reproduced this issue using the try build without patch on Win 10 x64. I can confirm the issue is fixed, tested with steps from comment 3, both tests passed successfully, tested on Win 10 x64 with Fx 88 beta and release channel.