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

third_party/coverage-3.7.1/coverage/files.py

Index: third_party/coverage-3.7.1/coverage/files.py
diff --git a/third_party/coverage-3.6/coverage/files.py b/third_party/coverage-3.7.1/coverage/files.py
similarity index 90%
rename from third_party/coverage-3.6/coverage/files.py
rename to third_party/coverage-3.7.1/coverage/files.py
index 3a3a7732afefed32706046118713357ee8f9ae54..464535a81653ca833ba33b462467941e373c0927 100644
--- a/third_party/coverage-3.6/coverage/files.py
+++ b/third_party/coverage-3.7.1/coverage/files.py
@@ -3,6 +3,7 @@
 from coverage.backward import to_string
 from coverage.misc import CoverageException
 import fnmatch, os, os.path, re, sys
+import ntpath, posixpath
 
 class FileLocator(object):
     """Understand how filenames work."""
@@ -110,13 +111,20 @@ else:
         """The actual path for non-Windows platforms."""
         return filename
 
+
 def abs_file(filename):
     """Return the absolute normalized form of `filename`."""
-    path = os.path.abspath(os.path.realpath(filename))
+    path = os.path.expandvars(os.path.expanduser(filename))
+    path = os.path.abspath(os.path.realpath(path))
     path = actual_path(path)
     return path
 
 
+def isabs_anywhere(filename):
+    """Is `filename` an absolute path on any OS?"""
+    return ntpath.isabs(filename) or posixpath.isabs(filename)
+
+
 def prep_patterns(patterns):
     """Prepare the file patterns for use in a `FnmatchMatcher`.
 
@@ -127,7 +135,6 @@ def prep_patterns(patterns):
     If `patterns` is None, an empty list is returned.
 
     """
-    patterns = patterns or []
     prepped = []
     for p in patterns or []:
         if p.startswith("*") or p.startswith("?"):
@@ -145,6 +152,10 @@ class TreeMatcher(object):
     def __repr__(self):
         return "<TreeMatcher %r>" % self.dirs
 
+    def info(self):
+        """A list of strings for displaying when dumping state."""
+        return self.dirs
+
     def add(self, directory):
         """Add another directory to the list we match for."""
         self.dirs.append(directory)
@@ -170,6 +181,10 @@ class FnmatchMatcher(object):
     def __repr__(self):
         return "<FnmatchMatcher %r>" % self.pats
 
+    def info(self):
+        """A list of strings for displaying when dumping state."""
+        return self.pats
+
     def match(self, fpath):
         """Does `fpath` match one of our filename patterns?"""
         for pat in self.pats:
@@ -223,6 +238,11 @@ class PathAliases(object):
         if pattern.endswith("*"):
             raise CoverageException("Pattern must not end with wildcards.")
         pattern_sep = sep(pattern)
+
+        # The pattern is meant to match a filepath.  Let's make it absolute
+        # unless it already is, or is meant to match any prefix.
+        if not pattern.startswith('*') and not isabs_anywhere(pattern):
+            pattern = abs_file(pattern)
         pattern += pattern_sep
 
         # Make a regex from the pattern.  fnmatch always adds a \Z or $ to
@@ -230,7 +250,7 @@ class PathAliases(object):
         regex_pat = fnmatch.translate(pattern).replace(r'\Z(', '(')
         if regex_pat.endswith("$"):
             regex_pat = regex_pat[:-1]
-        # We want */a/b.py to match on Windows to, so change slash to match
+        # We want */a/b.py to match on Windows too, so change slash to match
         # either separator.
         regex_pat = regex_pat.replace(r"\/", r"[\\/]")
         # We want case-insensitive matching, so add that flag.
@@ -283,7 +303,7 @@ def find_python_files(dirname):
             continue
         for filename in filenames:
             # We're only interested in files that look like reasonable Python
-            # files: Must end with .py, and must not have certain funny
+            # files: Must end with .py or .pyw, and must not have certain funny
             # characters that probably mean they are editor junk.
-            if re.match(r"^[^.#~!$@%^&*()+=,]+\.py$", filename):
+            if re.match(r"^[^.#~!$@%^&*()+=,]+\.pyw?$", filename):
                 yield os.path.join(dirpath, filename)