Switch cat command to use walk code.
The old syntax of "hg cat FILE REV" is now obsolete.
Use "hg cat -r REV FILE" instead, as for all other commands.
port:4:export
port:4:vaportight
port:4:import/export
FIXME: history is wrong here
port:1:1:-:eggs:import
port:1:2:+:eggs:vaportight
port:1:3:+:eggs:import/export
port:0:2:+:spam:export
port:0:1:+:spam:import
port:4:import/export