BZR_SSH environment variable is not explained in docs

bzr 1.1 rc1

C:\work\Bazaar>bzr help env-variables
Environment Variables

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BZRPATH Path where bzr is to look for shell plugin external commands.
BZR_EMAIL E-Mail address of the user. Overrides EMAIL.
EMAIL E-Mail address of the user.
BZR_EDITOR Editor for editing commit messages. Overrides EDITOR.
EDITOR Editor for editing commit messages.
BZR_PLUGIN_PATH Paths where bzr should look for plugins.
BZR_HOME Directory holding .bazaar config dir. Overrides HOME.
BZR_HOME (Win32) Directory holding bazaar config dir. Overrides APPDATA and HOME.
BZR_REMOTE_PATH Full name of remote 'bzr' command (for bzr+ssh:// URLs).
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There is no mention about BZR_SSH. As result it's not described in bzr_man (auto-generated User Reference).