When using docker-1.13.1-75.git8633870.el7_5 or higher, attempting to pull images when using a proxy results in the error "tls: first record does not look like a TLS handshake"

Issue

• After updating Red Hat's docker package to 1.13.1-88.git07f3374.el7 or higher, and utilizing an HTTP proxy, attempting to do a docker pull of images results in the following error:

# docker pull docker.io/busybox:latest
Trying to pull repository docker.io/library/busybox ...
Get https://registry-1.docker.io/v2/: proxyconnect tcp: tls: first record does not look like a TLS handshake

• Docker logs show a similar error:

# journalctl -u docker
Dec 10 04:08:13 test.com dockerd-current[24449]: time="2018-12-10T04:08:13.063946924-06:00" level=warning msg="Error getting v2 registry: Get https://registry.access.redhat.com/v2/: proxyconnect tcp: tls: first record does not look like a TLS handshake"

• This issue occurs when /etc/sysconfig/docker has proxies configured with both HTTP_PROXY and HTTPS_PROXY like so:

# grep -i HTTP /etc/sysconfig/docker
HTTP_PROXY='http://192.168.122.1:3128'
HTTPS_PROXY='https://192.168.122.1:3128