dmypy: Line number disappears when invoking multiple times

Bug Report

% dmypy restart
Daemon stopped
Daemon started
% dmypy run lib/testlib.py
lib/testlib.py:46: error: Unexpected attribute "xxxx" for model "Xxxx"
lib/testlib.py:142: error: The return type of a generator function should be "Generator" or one of its supertypes
Found 2 errors in 1 file (checked 945 source files)
% dmypy run lib/testlib.py
lib/testlib.py: error: The return type of a generator function should be "Generator" or one of its supertypes
lib/testlib.py:46: error: Unexpected attribute "xxxx" for model "Xxxx"
Found 2 errors in 1 file (checked 1 source file)

Note in the 2nd invocation lib/testlib.py: error: The return type of a generator function no longer has a line number.

To Reproduce

I tried reducing this to a smaller example, but failed to reproduce it that way. :(

Your Environment

• Mypy version used: 0.942
• Mypy command-line flags: (none)
• Mypy configuration options from mypy.ini (and other config files): I can reproduce this when I delete mypy config of my project
• Python version used: 3.10.2
• Operating system and version: macOS

Start by running the two successive dmypy run lib/testlib.py commands after dmypy restart, using the reported Python 3.10.2 setup and no mypy configuration. Compare the diagnostics for lib/testlib.py, especially the generator error that loses its line number on the second run. Done means repeated invocations preserve the line number while retaining the existing diagnostic output.