Fix stripDir p p /= Nothing bug

CHANGELOG

@@ -9,3 +9,6 @@
 0.4.0:
 	* Implemented stricter parsing, disabling use of "..".
 	* Made stripDir generic over MonadThrow
+
+0.5.0:
+	* Fix stripDir p p /= Nothing bug.

path.cabal

@@ -1,5 +1,5 @@
 name:                path
-version:             0.4.0
+version:             0.5.0
 synopsis:            Path
 description:         Path
 license:             BSD3
@@ -10,6 +10,7 @@ copyright:           2015 FP Complete
 category:            Filesystem
 build-type:          Simple
 cabal-version:       >=1.8
+extra-source-files:  README.md, CHANGELOG
 
 library
   hs-source-dirs:    src/

src/Path.hs

@@ -244,9 +244,10 @@ toFilePath (Path l) = l
 stripDir :: MonadThrow m
          => Path b Dir -> Path b t -> m (Path Rel t)
 stripDir (Path p) (Path l) =
-  case fmap Path (stripPrefix p l) of
+  case stripPrefix p l of
     Nothing -> throwM (Couldn'tStripPrefixDir p l)
-    Just ok -> return ok
+    Just "" -> throwM (Couldn'tStripPrefixDir p l)
+    Just ok -> return (Path ok)
 
 -- | Is p a parent of the given location? Implemented in terms of
 -- 'stripDir'. The bases must match.

test/Main.hs

@@ -101,6 +101,10 @@ operationStripDir =
                   ($(mkRelDir "bar/") </>
                    $(mkRelFile "bob/foo.txt")) ==
          Just $(mkRelFile "bob/foo.txt"))
+     it "stripDir parent parent = _|_"
+        (stripDir $(mkAbsDir "/home/chris/foo")
+                  $(mkAbsDir "/home/chris/foo") ==
+         Nothing)
 
 -- | The '</>' operation.
 operationAppend :: Spec