Fix expected output to match actual output for setuptools
and pip installation progress.  The progress line has been
one line for a while but the expected output was looking for
two lines.
Fix default args for py.test to be "tests" instead of using the
command name "test" also as the directory name to find tests.
Merge branch 'feature/testfix-1' into release/test_merging
Merge branch 'feature/testfix-2' into release/test_merging
Fix case where sys.exec_prefix is not a subdir of sys.prefix.
Skip copying required file if exec_prefix != prefix and
the file is sourced from exec_prefix.  Let the
copying/linking of exec_dir in install_python handle
these files.