fisheye doesnt handle p4 branch specs in ways that p4 supports

a relatively common use case for p4 branch specs is to move them around (edit, delete, etc). the branch specs are more of a temporary 'view' than a branch in other scms.

under this use case, fisheye can be very wrong in terms of ancestry of files and changesets.

we should at least have a system property to turn off branch spec support entirely. this would put every changeset on the 'head' branch, though you would still be able to see the repository structure at the directory level, and integrations would be tracked at the file level - so diffs of integrated files would show you what you expect to see.

the side effect of this is that the commit graph would show all commits in linear history. you wont be able to see integrations at the changeset level.