smart_clone: Bug when cloning files with directory prefixes

[thiagowfx]

Given:

$ smart_clone a/b/c/get_{foo,bar}.go

Produces the following:

$ hg st
A a.b.c/get_bar.go
  a/b/c/get_foo.go

Expected: Created a/b/c/get_bar.go.

Observed: Created a.b.c/get_bar.go - that is, a directory called a.b.c.