Merge Ben Finney's use-os-path-module fixes.

2 files changed, 6 insertions, 3 deletions

diff --git a/coverage/files.py b/coverage/files.py
index ba228c23..fb597329 100644
--- a/coverage/files.py
+++ b/coverage/files.py
@@ -6,7 +6,7 @@ class FileLocator(object):
     """Understand how filenames work."""
 
     def __init__(self):
-        self.relative_dir = self.abs_file(os.curdir) + os.sep
+        self.relative_dir = self.abs_file(os.curdir)
 
         # Cache of results of calling the canonical_filename() method, to
         # avoid duplicating work.
@@ -23,7 +23,9 @@ class FileLocator(object):
         FileLocator was constructed.
 
         """
-        return filename.replace(self.relative_dir, "")
+        common_prefix = os.path.commonprefix(
+            [filename, self.relative_dir + os.sep])
+        return filename[len(common_prefix):]
 
     def canonical_filename(self, filename):
         """Return a canonical filename for `filename`.
diff --git a/test/backtest.py b/test/backtest.py
index 12bdbc97..58b16474 100644
--- a/test/backtest.py
+++ b/test/backtest.py
@@ -29,7 +29,8 @@ else:
         if sys.hexversion > 0x03000000 and cmd.startswith("coverage "):
             # We don't have a coverage command on 3.x, so fix it up to call the
             # script. Eventually we won't need this.
-            cmd = "python " + sys.prefix + os.sep + "Scripts" + os.sep + cmd
+            script_path = os.path.join(sys.prefix, "Scripts", cmd)
+            cmd = "python " + script_path
 
         proc = subprocess.Popen(cmd, shell=True,
                 stdin=subprocess.PIPE, stdout=subprocess.PIPE,