4.6 -- 2021-09-23

• Documented official support for Debian 11 Bullseye, now that it is officially released by Debian upstream.
• Fixed installation on Debian 10 Buster. Upstream infrastructure had broken the Python virtualenv tool on this platform, which we've worked around for this release.
• Zulip releases are now distributed from https://download.zulip.com/server/, replacing the old www.zulip.org server.
• Added support for LDAP synchronization of the is_realm_owner and is_moderator flags.
• upgrade-zulip-from-git now uses git fetch --prune; this ensures upgrade-zulip-from-git master with return an error rather than using a stale cached version of the master branch, which was renamed to main this month.
• Added a new reset_authentication_attempt_count management command to allow sysadmins to manually reset authentication rate limits.
• Fixed a bug that caused the upgrade-postgresql tool to incorrectly remove supervisord configuration for process-fts-updates.
• Fixed a rare migration bug when upgrading from Zulip versions 2.1 and older.
• Fixed a subtle bug where the left sidebar would show both old and new names for some topics that had been renamed.
• Fixed incoming email gateway support for configurations with the http_only setting enabled.
• Fixed issues where Zulip's outgoing webhook, with the Slack-compatible interface, had a different format from Slack's documented interface.
• The installation and upgrade documentations now show the latest release's version number.
• Backported many improvements to the ReadTheDocs documentation.
• Updated translation data from Transifex.