contrib/debugshell.py

revset: predicate to avoid lookup errors

A query like

head() and (descendants("bad") and not descendants("fix"))

(testing if repo heads are affected by a bug) will abort with a
RepoLookupError if either badrev or fixrev aren't found inside
the repository, which is not very informative.

The new predicate returns an empty set for lookup errors, so

head() and (descendants(present("bad")) and not descendants(present("fix")))

will behave as wanted even if those revisions are not found.

# debugshell extension
"""a python shell with repo, changelog & manifest objects"""

import mercurial
import code

def debugshell(ui, repo, **opts):
    objects = {
        'mercurial': mercurial,
        'repo': repo,
        'cl': repo.changelog,
        'mf': repo.manifest,
    }
    bannermsg = "loaded repo : %s\n" \
                "using source: %s" % (repo.root,
                                      mercurial.__path__[0])
    code.interact(bannermsg, local=objects)

cmdtable = {
    "debugshell|dbsh": (debugshell, [])
}