This comment still isn't helpful. Saying that "we need to do this or things break" doesn't help a reader understand WHY it would break, merely that it does break. Try this instead:

`# Users can upload an archive containing their application or a directory containing their application. To see which case this is, we count how many files are present in the archive. As some platforms will inject a dot file into every directory, we shouldn't consider those when trying to find out if this archive is just a directory or not (because the presence of the dot file will cause our count to be incorrect).`

Presumably a more concise version of this could be done, but this is merely provided as an example to illustrate what a helpful comment would look like.