"last:number:branch" revision spec is not the same "revno:-number:branch"

[Andrew Bennetts]

According to http://bazaar-vcs.org/BzrRevisionSpec:

"last:number is the same as -number. last:1 means the last commited revision."

However, while "bzr diff -r revno:-2:path/to/branch..revno:-1:path/to/branch" works when the current working directory is not a branch, "bzr diff -r last:2:path/to/branch..last:1:path/to/branch" doesn't.

The difference in the code appears to be that RevisionSpec_last doesn't override needs_branch(), but RevisionSpec_revno does.

In fact, given that "last:" is defined in the documentation in terms of being the same as "revno:", except for negating the number, I'm surprised the code doesn't define RevisionSpec_last as inheriting from RevisionSpec_revno. The current structure makes it likely that there are other subtle differences (and makes it likely that as the code evolves, more differences will occur).

[John A Meinel (jameinel)]

Arguably, this is just a documentation bug.

last:X doesn't support branch portion last:X:path/to/branch