(stable) Catch more HTTP VCS errors and convert them into VCS repsonses
Ref T13590. Currently, errors arising from cluster locking (like the "stuck write lock" exception) are not caught and converted into VCS responses on the HTTP VCS workflow.
Catch a broader range of exceptions and convert them into appropriate responses.
- Forced a "stuck write lock" exception, pushed to a Git repository over HTTP.
- Before: generic fatal.
- After: VCS-specific fatal with a useful message in the "X-Phabricator-Message" response header.
Maniphest Tasks: T13590
Differential Revision: https://secure.phabricator.com/D21525