Summary:
If Mercurial 3.4+ is used to host repositories in Phabricator, any clients using 3.5+ will receive an exception after the bundle is pushed up. Clients will also fail to update phases for changesets pushed up.
Before directly responding to mercurial clients with all capabilities, this change filters out the 'bundle2' capability so the client negotiates using a legacy bundle wire format instead.
Test Plan:
Server: Mercurial 3.5
Client: Mercurial 3.4
Test with both HTTP and SSH protocols:
1. Create a local commit on client
2. Push commit to server
3. Verify the client emits something like:
```
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
```
Closes T9450
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin
Maniphest Tasks: T9450
Differential Revision: https://secure.phabricator.com/D14241