rm'ing conflicted files doesn't resolve conflicts

When a conflicted file is removed via `bzr rm`, I'd expect conflicts related to it to be resolved. But it doesn't. Nor does `bzr resolve`'s auto-resolving feature (as you might try after the above, or after a system `rm`). It requires a `resolve --all`.

Reproduce:
#!/bin/sh -x
bzr="/usr/local/bin/bzr --no-plugins --no-aliases"

# Create initial branch
${bzr} init A
(
    cd A ;
    mkdir a ;
    touch a/b ;
    ${bzr} add ;
    ${bzr} ci -m 'add A'
)

# Branch it and delete
${bzr} branch A B
(
    cd B ;
    rm -rf a ;
    ${bzr} ci -m 'clear in B'
)

# Change stuff in A
(
    cd A ;
    echo 'changes' > a/b ;
    ${bzr} ci -m 'change A'
)

# Merge the changes. Insist we don't want the files. Try to
# auto-resolve.
(
    cd B ;
    ${bzr} merge ;
    ${bzr} rm --force a ;
    # That alone should have resolved the conflicts, but it didn't:
    ${bzr} conflicts ;
    ${bzr} resolve ;
    # Certainly they should have been auto-resolved, but nope:
    ${bzr} conflicts ;
    # Gotta do --all:
    ${bzr} resolve --all ;
    ${bzr} conflicts
)