archive: support 'wdir()'
This is a step toward replacing the extdiff internals with archive, in order to
support 'extdiff -S'. Only Mercurial subrepos are supported for now.
If a file is missing from the filesystem, it is silently skipped. Perhaps it
should warn, but it cannot abort when working with extdiff because deleting a
file is a legitimate diff.
fixbundle() {
grep -v 'saving bundle' | grep -v 'saved backup' | \
grep -v added | grep -v adding | \
grep -v "unable to find 'e' for patching" | \
grep -v "e: No such file or directory"
}