importers: flymake files break gitinfo

*_flymake.py files are found by the catchall *.py when the importers scan for files relevant to their functionality. As they are not under version control, they produce invalid output from git_info

Possible solutions:

• Modify git_info to ignore them
• Use the .gitignore file as a filter for the files this might be problematic with files added in spite of the ignore file