convert: adjust progress bar for octopus merges (issue4169) For merges, we walk the files N-1 times, where N is the number of parents. This means that for an octopus merge with 3 parents and 2 changed files, we actually fetch 6 files. This corrects the progress output of the convert command when such commits are encountered.

test-convert-git: show insane progress bar with octopus merge (issue4169) This is done as a separate change from the fix so that it's obvious what is corrected by the bugfix.

manifest: have context use self.hasdir() A couple places in context currently use "x in self._dirs" to check for the existence of the directory, but this requires that all directories be loaded into a dict. Calling hasdir() instead puts the work on the the manifest to check for the existence of a directory in the most efficient manner.

manifest: add hasdir() to context This is a convenience method that calls to its manifest's hasdir(). There are parts of context that check to see if a directory exists, and this method will let implementations of manifest provide an optimal way to find a particular directory.