tests/sitecustomize.py

memctx: calculate manifest correctly with newly-removed files (issue4470)

Before this patch, "memctx._manifest" tries to get (and use normally)
filectx also for newly-removed files, even though "memctx.filectx()"
returns None for such files.

To calculate manifest correctly even with newly-removed files, this
patch does:

  - replace "man.iteritems()" for the loop by "self._status.modified"
    to avoid accessing itself to newly removed files

    this also reduces loop cost for large manifest.

  - remove files in "self._status.removed" from the manifest

In this patch, amending is confirmed twice to examine both (1) newly
removed files and (2) ones already removed in amended revision.

try:
    import coverage
    getattr(coverage, 'process_startup', lambda: None)()
except ImportError:
    pass