texpresso-tonic build error in Rust 1.7.0. : No method named 'as_encoded_bytes' (src/bin/tectonic/v2cli.rs)

[sambaPython24]

Build error on Rust 1.7.0. : No method named 'as_encoded_bytes'

I did not find, which Rust version you used to compile ``make texpresso-tonic```but on 1.7.0. I get the

   Compiling tectonic v0.15.0 (/.../texpresso/tectonic)
error[E0599]: no method named `as_encoded_bytes` found for reference `&OsStr` in the current scope
   --> src/bin/tectonic/v2cli.rs:515:61
    |
515 | ...                   let mut path = path.as_os_str().as_encoded_bytes();
    |                                                       ^^^^^^^^^^^^^^^^ method not found in `&OsStr`

For more information about this error, try `rustc --explain E0599`.
error: could not compile `tectonic` (bin "texpresso-tonic") due to previous error
make[1]: *** [Makefile.tectonic:11: tectonic] Error 101
make[1]: Leaving directory '/.../texpresso'
make: *** [Makefile:55: texpresso-tonic] Error 2

Which rust version do you use and is there an alternative for as_encoded_bytes?