False-positive in `file` attribute detection

[rossburton]

Not sure if there's a way to detect this, but thought I'd file it anyway.

Clone https://git.openembedded.org/openembedded-core and run vermin:

$ vermin --target=3.8 --lint -vvv meta/lib/oeqa/selftest/cases/manifest.py
Detecting python files..
Analyzing using 128 processes..
2.7, !3      /home/rosbur01/Yocto/openembedded-core/meta/lib/oeqa/selftest/cases/manifest.py
  L124: 'file' member requires 2.0, !3

Line 124:

msg = '{}: {} Error has the following missing entries'.format(self.classname, m_entry[k].file)

Note that m_entry[k] is a ManifestEntry instance, which has an explicit file member.

Can vermin detect this, or should we annotate the accesses (or rename the member).