Clippy Fix: let_underscore_lock
Clippy Fix: let_underscore_lock

Use _variable instead of _ as a variable name for lock.

Expl.: https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_lock

Signed-off-by: Matthias Beyer <1d6e1cf70ec6f9ab28d3ea4b27a49a77654d370e@beyermatthias.de>

matthiasbeyer/imag,matthiasbeyer/imag