BUG #16956: psql won't load command history

The following bug has been logged on the website:

Bug reference:      16956
Logged by:          Robin Knipe
Email address:      robin.knipe@gmail.com
PostgreSQL version: 12.6
Operating system:   kubuntu-18.04.2, docker postgres:12-alpine
Description:

Running the `psql` command from docker (postgres:12-alpine), fails to load
the `.psql_history` command contents. Strangely, the session's commands ARE
SAVED though! Also I can read the history contents in the psql session, as
the following raw output shows:
```
levqa=> \echo `echo $PSQL_HISTORY`
/.psql_history
levqa=> \echo `tail $PSQL_HISTORY`
_HiStOrY_V2_
_HiStOrY_V2_
_HiStOrY_V2_
_HiStOrY_V2_
echo\040HISTCONTROL\012;
`echo\040HISTCONTROL`\012;
\134echo\040:HISTCONTROL
\134echo\040:HISTFILE
\134set\040HISTFILE\040/.psql_history
\134echo\040:HISTFILE
levqa=>
```

FYI: the docker command I'm running:
```
docker run \
  -it \
  --entrypoint=bash \
  --network=host \
  --mount type=bind,source="$( ls ~/.psql_history )",target="/.psql_history"
\
  -e PGPASSWORD="${PASS}" \
  -e PSQL_HISTORY="/.psql_history" \
  postgres:12-alpine \
    -wh localhost \
    "${NAME}" \
    "${USER}"
```