[Bug-apl] native function lib_file_io reload not working

[David B. Lamkins]

      'lib_file_io' ⎕fx 'pkg⍙fileio'
pkg⍙fileio
      )erase pkg⍙fileio
      'lib_file_io' ⎕fx 'pkg⍙fileio'
pkg⍙fileio
      pkg⍙fileio⍬
VALUE ERROR
      pkg⍙fileio⍬
      ^