wait-for-it: not working on alpine 3.10 with bash installed

we use wait-for-it.sh heavily in CI for docker integration testing in golang. Recently a job broke due to wait-for-it.sh error. I believe the issue may have to do with something changing in timeout from alpine3.9 (works) to alpine 3.10 (not working). In both cases we were installing bash with apk.

Repro (note in vi I am copying wait-for-it from current master)

$ docker run -it --rm golang:1.12-alpine
/go # vi wait-for-it.sh
/go # chmod +x wait-for-it.sh 
/go # apk update && apk add --no-cache bash
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/community/x86_64/APKINDEX.tar.gz
v3.10.1-11-g89d0862481 [http://dl-cdn.alpinelinux.org/alpine/v3.10/main]
v3.10.1-12-ga885fe876c [http://dl-cdn.alpinelinux.org/alpine/v3.10/community]
OK: 10327 distinct packages available
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/community/x86_64/APKINDEX.tar.gz
(1/5) Installing ncurses-terminfo-base (6.1_p20190518-r0)
(2/5) Installing ncurses-terminfo (6.1_p20190518-r0)
(3/5) Installing ncurses-libs (6.1_p20190518-r0)
(4/5) Installing readline (8.0.0-r0)
(5/5) Installing bash (5.0.0-r0)
Executing bash-5.0.0-r0.post-install
Executing busybox-1.30.1-r2.trigger
OK: 15 MiB in 20 packages
/go # ./wait-for-it.sh docker:5432
timeout: unrecognized option: t
BusyBox v1.30.1 (2019-06-12 17:51:55 UTC) multi-call binary.

Usage: timeout [-s SIG] SECS PROG ARGS

Runs PROG. Sends SIG to it if it is not gone in SECS seconds.
Default SIG: TERM.
wait-for-it.sh: timeout occurred after waiting 15 seconds for docker:5432

Workaround: I was able to work around this issue by installing coreutils as well which updates timeout (continuing from example above)

/go # apk update && apk add --no-cache coreutils
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/community/x86_64/APKINDEX.tar.gz
v3.10.1-11-g89d0862481 [http://dl-cdn.alpinelinux.org/alpine/v3.10/main]
v3.10.1-12-ga885fe876c [http://dl-cdn.alpinelinux.org/alpine/v3.10/community]
OK: 10327 distinct packages available
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/community/x86_64/APKINDEX.tar.gz
(1/3) Installing libacl (2.2.52-r6)
(2/3) Installing libattr (2.4.48-r0)
(3/3) Installing coreutils (8.31-r0)
Executing busybox-1.30.1-r2.trigger
OK: 16 MiB in 23 packages
/go # ./wait-for-it.sh -t 15 docker:5432
wait-for-it2.sh: waiting 15 seconds for docker:5432
wait-for-it2.sh: timeout occurred after waiting 15 seconds for docker:5432