bug in grep handling [^^] (not caret) character class

[Ivan Heffner]

grep (v2.4.2) appears to have a problem trying to match [^^].

Expected:
If I have a file foo.txt that contains lines with a single character on
each line, I should be able to find all lines that do not contain a
caret by doing
 
   grep '^[^^]$' foo.txt
 
Actual:
This command returns lines that contain a single caret.  In fact, if I
have all alpha-numeric and standard US symbols by them selves on
different lines, this grep will only return 
$ grep '^[^^]$' foo.txt
^
-
[end]
 
Ivan Heffner