Upgrade to coverage 3.7.1 and have it auto-build itself on first use.

third_party/coverage-3.6/coverage/backward.py

Index: third_party/coverage-3.6/coverage/backward.py
diff --git a/third_party/coverage-3.6/coverage/backward.py b/third_party/coverage-3.6/coverage/backward.py
deleted file mode 100644
index 2c015af2ba1bcdb9897a78f291929c21397398fd..0000000000000000000000000000000000000000
--- a/third_party/coverage-3.6/coverage/backward.py
+++ /dev/null
@@ -1,147 +0,0 @@
-"""Add things to old Pythons so I can pretend they are newer."""
-
-# This file does lots of tricky stuff, so disable a bunch of lintisms.
-# pylint: disable=F0401,W0611,W0622
-# F0401: Unable to import blah
-# W0611: Unused import blah
-# W0622: Redefining built-in blah
-
-import os, re, sys
-
-# Python 2.3 doesn't have `set`
-try:
-    set = set       # new in 2.4
-except NameError:
-    from sets import Set as set
-
-# Python 2.3 doesn't have `sorted`.
-try:
-    sorted = sorted
-except NameError:
-    def sorted(iterable):
-        """A 2.3-compatible implementation of `sorted`."""
-        lst = list(iterable)
-        lst.sort()
-        return lst
-
-# rpartition is new in 2.5
-try:
-    "".rpartition
-except AttributeError:
-    def rpartition(s, sep):
-        """Implement s.rpartition(sep) for old Pythons."""
-        i = s.rfind(sep)
-        if i == -1:
-            return ('', '', s)
-        else:
-            return (s[:i], sep, s[i+len(sep):])
-else:
-    def rpartition(s, sep):
-        """A common interface for new Pythons."""
-        return s.rpartition(sep)
-
-# Pythons 2 and 3 differ on where to get StringIO
-try:
-    from cStringIO import StringIO
-    BytesIO = StringIO
-except ImportError:
-    from io import StringIO, BytesIO
-
-# What's a string called?
-try:
-    string_class = basestring
-except NameError:
-    string_class = str
-
-# Where do pickles come from?
-try:
-    import cPickle as pickle
-except ImportError:
-    import pickle
-
-# range or xrange?
-try:
-    range = xrange
-except NameError:
-    range = range
-
-# A function to iterate listlessly over a dict's items.
-if "iteritems" in dir({}):
-    def iitems(d):
-        """Produce the items from dict `d`."""
-        return d.iteritems()
-else:
-    def iitems(d):
-        """Produce the items from dict `d`."""
-        return d.items()
-
-# Exec is a statement in Py2, a function in Py3
-if sys.version_info >= (3, 0):
-    def exec_code_object(code, global_map):
-        """A wrapper around exec()."""
-        exec(code, global_map)
-else:
-    # OK, this is pretty gross.  In Py2, exec was a statement, but that will
-    # be a syntax error if we try to put it in a Py3 file, even if it is never
-    # executed.  So hide it inside an evaluated string literal instead.
-    eval(
-        compile(
-            "def exec_code_object(code, global_map):\n"
-            "    exec code in global_map\n",
-            "<exec_function>", "exec"
-            )
-        )
-
-# Reading Python source and interpreting the coding comment is a big deal.
-if sys.version_info >= (3, 0):
-    # Python 3.2 provides `tokenize.open`, the best way to open source files.
-    import tokenize
-    try:
-        open_source = tokenize.open     # pylint: disable=E1101
-    except AttributeError:
-        from io import TextIOWrapper
-        detect_encoding = tokenize.detect_encoding  # pylint: disable=E1101
-        # Copied from the 3.2 stdlib:
-        def open_source(fname):
-            """Open a file in read only mode using the encoding detected by
-            detect_encoding().
-            """
-            buffer = open(fname, 'rb')
-            encoding, _ = detect_encoding(buffer.readline)
-            buffer.seek(0)
-            text = TextIOWrapper(buffer, encoding, line_buffering=True)
-            text.mode = 'r'
-            return text
-else:
-    def open_source(fname):
-        """Open a source file the best way."""
-        return open(fname, "rU")
-
-
-# Python 3.x is picky about bytes and strings, so provide methods to
-# get them right, and make them no-ops in 2.x
-if sys.version_info >= (3, 0):
-    def to_bytes(s):
-        """Convert string `s` to bytes."""
-        return s.encode('utf8')
-
-    def to_string(b):
-        """Convert bytes `b` to a string."""
-        return b.decode('utf8')
-
-else:
-    def to_bytes(s):
-        """Convert string `s` to bytes (no-op in 2.x)."""
-        return s
-
-    def to_string(b):
-        """Convert bytes `b` to a string (no-op in 2.x)."""
-        return b
-
-# Md5 is available in different places.
-try:
-    import hashlib
-    md5 = hashlib.md5
-except ImportError:
-    import md5
-    md5 = md5.new