mypy erroneously reports no [mypy] section in config file unless --config-file is specified

[Simon Lambourn]

Using mypy 0.670 installed via pip.
I created a file~/.config/mypy/config/mypy.ini containing a [mypy] section and one setting (mypy_path).

If I use python3 -m mypy [module to check]
I get an error:

[~]/.config/mypy/config: No [mypy] section in config file

Whereas if I use python3 -m mypy [module to check] --config-file ~/.config/mypy/config/mypy.ini
there is no error message and the config file is processed.

Expected behaviour:
No error message if the file contains a [mypy] section

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: mypy (not installed)
ProcVersionSignature: Ubuntu 5.0.0-25.26-generic 5.0.18
Uname: Linux 5.0.0-25-generic x86_64
ApportVersion: 2.20.10-0ubuntu27.1
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Aug 26 12:07:42 2019
SourcePackage: mypy
UpgradeStatus: Upgraded to disco on 2019-04-25 (123 days ago)

[Michael R. Crusoe (misterc)]

I can confirm that this behavior still exists in mypy 0.781