R1:972604e0e59c

Set `TERM` to prevent `No entry for terminal type "unknown"` messages during fetch

Summary:
Fetches cause output in `/var/tmp/phd/log/daemons.log` as
follows:
```
PHLOG: 'Unexpected output while updating repository "rREPONAME": No entry for terminal type "unknown";
using dumb terminal settings.
' at [/path/to/phabricator/src/applications/repository/daemon/PhabricatorRepositoryPullLocalDaemon.php:455]
```

These warnings come from PHP itself. Silence these warnings by providing a
known value for `TERM`…