fixup! X wcfs: Run fusermount and friends with /bin:/usr/bin always on path

wcfs/__init__.py

@@ -509,7 +509,7 @@ def _fuse_unmount(mntpt):
             if lsof.returncode:
                 log.warn("(lsof failed)")
         defer(_)
-        raise
+        raise RuntimeError("fuse_unmount %s failed  (logged details)" % mntpt)
 
 # _is_mountpoint returns whether path is a mountpoint
 def _is_mountpoint(path):    # -> bool