Tags and their meanings in Gitano rules
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The following tags have defined meaning:

gitano/operation
	The operation being requested.
	Values for this include:

	createrepo  --  Attempt to create a repository
	read -- Attempt to read from a repository
	write -- Attempt to write to a repository
	createref -- Attempt to create a ref
	updaterefff -- A specifically fast-forward ref update
	updaterefnonff -- A non-fastforward ref update
	deleteref -- Attempt to delete a ref

gitano/source
	The source of the operation being requested
	Values for this might be 'ssh' for a direct SSH command, or otherwise
	the name of a command being run.

gitano/user
	The username under which this operation is being done.
	This is typically set by the incoming SSH operation but under some
	circumstances it might be another username for server-side commands.

gitano/groups
	The groups that the user is a member of -- This includes any group
	whose membership expands to include this user, including groups which
	include groups whose membership includes the user.
	The groups are all separated by a forward-slash and the whole string
	is enclosed by them.  As such, matches such as "/group-name/" will
	work to match group names exactly, whereas "/prefix-[^/]+/" must be
	used if you meant to do a clean prefix match.

gitano/ref
	The ref being created/deleted/updated.

gitano/starttree
	When an operation alters a set of files then gitano will include the
	start tree's fileset here.  The files will be null-separated and
	the list enclosed with nulls, allowing list matches.

gitano/targettree
	When an operation alters a set of files then this will like the
	gitano/starttree tag, but will contain the tree of the target ref.

gitano/treediff/...
	When an operation alters a set of files, this contains a set of tags
	which represent the delta.

	.../targets   ->  List of files which are "targets" of delta ops.
	.../added     ->  Specifically files which are explicitly added or
                          are targets of 100% copies
	.../deleted   ->  Specifically files which are explicitly deleted
	.../modified  ->  Purely modified files (also targets of non 100% R/C)
	.../renamed   ->  Sources of renamed files
	.../renamedto ->  Targets of renamed files

	.../kind/TNAME -> Entry kind of TNAME (blob, xblob, symlink, commit)
	.../oldkind/TNAME -> Old kind of TNAME