Handle edge case: Zero width delimiter

base/strings/util.jl

@@ -625,6 +625,7 @@ julia> collect(eachrsplit(a, ".")) == ["ch", "r", "Ma"]
 true
 
 julia> collect(eachrsplit(a, "."; limit=2)) == ["ch", "Ma.r"]
+true
 ```
 """
 function eachrsplit end
@@ -668,7 +669,12 @@ function Base.iterate(it::RSplitIterator, (to, remaining_splits)=(lastindex(it.s
  break
  else
  from = nextind(it.str, last(pos))
- next_to = prevind(it.str, first(pos))
+ # pos can be empty if we search for a zero-width delimiter, in which
+ # case pos is to:to-1.
+ # In this case, next_to must be to - 1, except if to is 0 or 1, in
+ # which case, we must stop iteration for some reason.
+ next_to = (isempty(pos) & (to < 2)) ? -1 : prevind(it.str, first(pos))
+
  # If the element we emit is empty, discard it based on keepempty
  if from > to && !(it.keepempty)
  to = next_to