tests/failfilemerge.py

rust-config: add support for default config items

Now that configitems.toml exists, we can read from it the default values for
all core config items.

We will add the devel-warning for use of undeclared config items in a later
patch when we're done adding the missing entries for `rhg`.

# extension to emulate interrupting filemerge._filemerge


from mercurial import (
    error,
    extensions,
    filemerge,
)


def failfilemerge(*args, **kwargs):
    raise error.Abort(b"^C")


def extsetup(ui):
    extensions.wrapfunction(filemerge, 'filemerge', failfilemerge)