REGR: show_versions
regression in #31660 (no need to backport)

master
```
INSTALLED VERSIONS
------------------
{k:<17}: {stat}
{k:<17}: {stat}
{k:<17}: {stat}
...
```

this PR
```
INSTALLED VERSIONS
------------------
commit           : b11e0647d42a27c279f3c46d5ce26d79bb5f5dec
python           : 3.7.4.final.0
python-bits      : 64
...
```
