tests/hgweberror.py

run-tests: stop writing a `python3` symlink pointing to python2

Having `python3` actually pointing to `python2` is bad. So we stop doing so.

In addition we need to re-introduce a `python` executable since some of the
script really need to be able to say "current python" in their shbang. For
example, `hghave` is one of such script.

The faulty changes where introduced by c102b704edb5.

Differential Revision: https://phab.mercurial-scm.org/D10943

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

from __future__ import absolute_import

from mercurial.hgweb import webcommands


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

    # Simulate an error after partial response.
    if b'partialresponse' in web.req.qsparams:
        web.res.status = b'200 Script output follows'
        web.res.headers[b'Content-Type'] = b'text/plain'
        web.res.setbodywillwrite()
        list(web.res.sendresponse())
        web.res.getbodyfile().write(b'partial content\n')

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


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