`replace-regexp-in-string' sometimes signals an error when REGEXP
contains some bondary sequence.  Difference of searches between
against an original passed string and against an extracted substring
causes the incident.


(replace-regexp-in-string-simple "a\\B" "A" "a aaaa")
	error --> cons: Args out of range: 2, 3
    expected
	==> "a AAAa"

(replace-regexp-in-string "\\Ba" "A" "a aaaa")
	error --> cons: Args out of range: 3, 4
    expected
	==> "a aAAA"

--
Shigeru