Swap out hard tabs for spaces

Instead of reasing a new exception, just augment the existing exception, avoiding any concerns about exception type, but still communicating the context necessary to trace the issue. Ref #537.

This helps finding packages with bad utf

Stop comparing repr()'s in TestEntryPoint

Adjust expectation that 'extra' is not in the marker evaluation if no extras demanded the requirement.

Reinstate the or guard in WorkingSet._markers_pass

Checking hundreds of possibly installed packages manually should NOT be expected of the user ;)

In Python 3, the default order of iterables can not determined,
so comparing the repr of objects that include tuples is not static
like it is under Python 2. Compare the attributes of EntryPoint
instead, making sure to sort .attrs and .extras.

Closes: #526

Restore evaluating environment markers in WorkingSet

Correctly deal with parsed requirements that include extras as a
marker inside WorkingSet that are populated from METADATA inside
wheels, like we get from pip>=7.

This partially reverts commit 04d10ff0.

Closes: #523

Drop unused safe_repr function

When _assertIn was removed from test_resources, the safe_repr
function was not dropped, leaving it with no callers, so drop it.

--HG--
branch : distribute

Update vendored packaging to 16.6