fix for cloud paths

The _check_path_matches_patterns function was failing for cloud (e.g.
s3, gc3) URIs.

 1) the path.relative_to() function doesn't work for cloud URIs
(it just returns the original).
 2) combining Path('/') with the result of relative_to now also throws
an error when using cloud (or non-posix) paths.

This fix drops the uri prefix by using .path to get the posix-like
part of the path, so that the regex check works as expected.

bids/layout/index.py

@@ -41,12 +41,17 @@ def _extract_entities(bidsfile, entities):
 
 def _check_path_matches_patterns(path, patterns, root=None):
     """Check if the path matches at least one of the provided patterns. """
+
     if not patterns:
         return False
 
     path = path.absolute()
     if root is not None:
-        path = Path("/") / path.relative_to(root)
+
+        if isinstance(path,Path):
+            path = Path("/") / Path(path.path).relative_to(Path(root.path))
+        else:
+            path = Path("/") / path.relative_to(root)
 
     # Path now can be downcast to str
     path = str(path)

setup.py

@@ -3,6 +3,6 @@
 import versioneer
 
 setup(
-    version=versioneer.get_version(),
+    version="0.17.2-dev",
     cmdclass=versioneer.get_cmdclass(),
 )