fix bestrelpath related tests and docstrings

--HG--
branch : 1.0.x

py/code/testing/test_excinfo.py

@@ -638,7 +638,9 @@ raise ValueError()
             repr = excinfo.getrepr(abspath=False)
             repr.toterminal(tw)
             line = tw.lines[-1]
-            assert line == "mod.py:3: ValueError" 
+            x = py.path.local().bestrelpath(path) 
+            if len(x) < len(str(path)):
+                assert line == "mod.py:3: ValueError" 
 
             repr = excinfo.getrepr(abspath=True)
             repr.toterminal(tw)

py/path/common.py

@@ -152,14 +152,14 @@ class PathBase(object):
         return ""
 
     def bestrelpath(self, dest): 
-        """ return relative path from self to dest
-            such that self.join(bestrelpath) == dest. 
+        """ return a string which is a relative path from self 
+            to dest such that self.join(bestrelpath) == dest and 
             if not such path can be determined return dest. 
         """ 
         try:
             base = self.common(dest)
             if not base:  # can be the case on windows
-                return dest
+                return str(dest)
             self2base = self.relto(base)
             reldest = dest.relto(base)
             if self2base:
@@ -172,7 +172,7 @@ class PathBase(object):
             target = dest.sep.join(l)
             return target 
         except AttributeError:
-            return dest
+            return str(dest)
 
 
     def parts(self, reverse=False):