Map values with integer keys cannot be read

Reproduction:

let map: hmap[] = []
let map[aa] = bb
let map[11] = 22

echo @map      # Prints "11 22 aa bb"
echo @map[aa]  # Prints "bb"
echo @map[11]  # Prints nothing, should print "22"

Build information:

rustc -V: rustc 1.33.0-nightly (4c2be9c97 2019-01-22)

git rev-parse HEAD: 32319d7b