Inconsistent behavior of ~. and special code failure

[mlochbaum]

See this J forum post for full details. Inconsistencies in how ~. and /. handle arguments with tolerantly equal elements. In particular, the following results are dangerously incorrect.

   tb =: 1+2e_14*i:3
   #tb
7
   #/.~ 1+2e_14*i:3  NB. sum of group lengths should be total length
3
   (#,{.)/.~ tb  NB. Should not fail
|length error
|       (#,{.)/.~tb