s3ls s3 path completion broken

[tilusnet]

It doesn't seem to split suggestions at prefix '/' boundaries.

E.g. with

bucket
  / pfx1
    / pfx11
      / file111
      / file112
    / pfx12
  / pfx2

typing s3ls s3://bucket/pfx<TAB> will give me e.g. s3ls s3://bucket/pfx1/pfx11/file1 instead of suggesting

s3://bucket/pfx1 
s3://bucket/pfx2