Initialize package before calling find_spec() for __main__, so that we do not
incorrectly handle exceptions from __init__.py. When runpy is used from the
Python CLI, use an internal exception rather than ImportError, to avoid
catching unexpected exceptions.

Also remove exception message rewriting in _run_module_as_main(), because it
seems to be redundant with the _get_main_module_details() function.

Issue #25715: Python 3.5.1 installer shows wrong upgrade path and incorrect logic for launcher detection.

Output raised exception at verbose level 2 (-vv).

Output raised exception at verbose level 2 (-vv).

Output raised exception at verbose level 2 (-vv).

Patch by Stéphane Wirtel.

by Marian Ganisin.

by Marian Ganisin.

by Marian Ganisin.

Previous documentation was not clear if the geturl(), info() and getcode()
were valid for HTTP responses. The “msg” attribute is different to the usual
HTTPResponse.msg attribute. Based on patch by Evens Fortuné.