Correctly estimate required space for string
Correctly estimate required space for string

`.len()` returns length in bytes so it overestimates the required space
aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust