tests/hgweberror.py

mq: use dirstateguard instead of dirstate.invalidate (qrefresh)

Before this patch, "mq.queue.refresh()" uses "dirstate.invalidate()"
as a kind of "restore .hg/dirstate to the original status" during a failure.

But it just discards changes in memory, and doesn't actually restore
".hg/dirstate". Then, it can't work as expected, if "dirstate.write()"
is executed while processing.

This patch uses "dirstateguard" instead of "dirstate.invalidate()" to
restore ".hg/dirstate" during a failure even if "dirstate.write()" is
executed before a failure.

This patch also removes "beginparentchage()" and "endparentchange()",
because "dirstateguard" makes them useless.

This is a part of preparations to fix the issue that the recent (in
memory) dirstate isn't visible to external processes (e.g. "precommit"
hook).

# A dummy extension that installs an hgweb command that throws an Exception.

from mercurial.hgweb import webcommands

def raiseerror(web, req, tmpl):
    '''Dummy web command that raises an uncaught Exception.'''

    # Simulate an error after partial response.
    if 'partialresponse' in req.form:
        req.respond(200, 'text/plain')
        req.write('partial content\n')

    raise AttributeError('I am an uncaught error!')

def extsetup(ui):
    setattr(webcommands, 'raiseerror', raiseerror)
    webcommands.__all__.append('raiseerror')