number of developers metric is way off for repositories like linux

[tofferrosen]

For instance, in the linux repository, drivers/net/usb/qmi_wwan.c does not have 2,210 developers.

[niekvanderlaan]

I think this bug is caused in ingester/git.py, where you apply the following logic:

setattr(prevFileChanged, 'authors', authors)

however, authors is the list of all authors that touched the files changed in the current files. I think this is resolved by appending the author of the current commit to prevAuthors, and assign prevAuthors to the authors attribute. i.e.:

prevAuthors.append(author)
setattr(prevFileChanged, 'authors', prevAuthors)

EDIT:
this error is also made in the else case, i.e. when creating a new CommitFile:

fileObject = CommitFile(fileName, fileLa - fileLd, authors, unixTimeStamp)

Following this logic, the authors of the file are equal to all previous authors of all files changed in the current commit. This should therefore be updated to:

fileObject = CommitFile(fileName, fileLa - fileLd, [author], unixTimeStamp)

Furthermore, I would suggest storing the authors in sets, rather than lists. This makes for efficient lookup of whether an author is in the set of authors, rather than explicitly checking it by traversing the entire list.