/bin/sh on Alpine 3.6 behave differently

Hey, faced issue today, that env variables with dots being lost when passed via /bin/sh on alpine:3.6

Behaviour with 3.6:

$ docker run --rm -it -e test.var=alpine alpine:3.6 /bin/sh -c 'env'
no_proxy=*.local, 169.254/16
HOSTNAME=a9a7839295a3
SHLVL=1
HOME=/root
TERM=xterm
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/

Behaviour with 3.5:

$ docker run --rm -it -e test.var=alpine alpine:3.5 /bin/sh -c 'env'
no_proxy=*.local, 169.254/16
HOSTNAME=f5e81d7240ae
SHLVL=1
HOME=/root
TERM=xterm
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
test.var=alpine
PWD=/

Is it expected?

PS: /bin/sh on the ubuntu loosing variables with dots too.

(from redmine: issue id 7344, created on 2017-05-29, closed on 2017-05-30)