.png files in comments are expected to exist in test folder

I am using 1.0.1 Beta1 running on Mac book Pro OS X 10.9.3

If I have line like

# xyz.png

in my Python test script

then my test is not loaded with a message indicating that xyz.png is not in the test folder.

If I want to capture an image and save it to a file new.png then too the load fails
with a message telling me that new.png is not in the test folder.

It appears that every string with .png extension is deemed to be a required file.

Is this expected behavior?