When Hudson jobs fail or hang due to inexplicable Mercurial errors, it would be
very helpful to get debug output from Mercurial. Most commands use --quiet to
suppress irrelevant output from the build log. Should have a global (or
per-tool?) option to run with --verbose or --debug.

In a few cases, the launcher has to override this anyway; e.g. Hg 0.9.x has a
bug requiring --debug for incoming to work correctly.