use commit time as mtime for file archives.
now output from two run of "hg archive -t zip" is same.
port:4:exportport:4:vaportightport:4:import/exportFIXME: history is wrong hereport:1:1:-:eggs:importport:1:2:+:eggs:vaportightport:1:3:+:eggs:import/exportport:0:2:+:spam:exportport:0:1:+:spam:importport:4:import/export