crecord: remove skipfolded keyword argument from patchnode.previtem()

It wasn't used, it wasn't implemented. Probably was a copy-paste bonus from
patchnode.nextitem()

mercurial/crecord.py

@@ -164,7 +164,7 b' class patchnode(object):'
             except AttributeError: # parent and/or grandparent was None
                 return None
 
-    def previtem(self, constrainlevel=True, skipfolded=True):
+    def previtem(self, constrainlevel=True):
         """
         If constrainLevel == True, return the closest previous item
         of the same type where there are no items of different types between
@@ -174,10 +174,6 b' class patchnode(object):'
         closest to this item, regardless of item's type (header, hunk, or
         HunkLine).
 
-        If skipFolded == True, and the current item is folded, then the items
-        that are hidden due to folding will be skipped when determining the
-        next item.
-
         If it is not possible to get the previous item, return None.
         """
         if constrainlevel: