revlog.revision: avoid opening the datafile without need.
If there's no inline data, revlog.revision opens the data file every
time it's called. This is useful if we're going to call chunk many
times, but, if we're going to call it only once, it's better to let
chunk open the file - if we're lucky, all the data we're going to need
is already cached and we won't need to even look at the file.
default = 'changelog'
feedupdated = '<updated>#date|rfc3339date#</updated>'
mimetype = 'application/atom+xml; charset={encoding}'
header = header.tmpl
changelog = changelog.tmpl
changelogentry = changelogentry.tmpl
filelog = filelog.tmpl
filelogentry = filelogentry.tmpl
tags = tags.tmpl
tagentry = tagentry.tmpl