POST mime/multipart upload style can have filename value optional
which leads to implementation issues in Go releases in their
standard mime/multipart library.
When `filename` doesn't exist Go doesn't update `form.File` which
we rely on to extract the incoming file data, strangely when `filename`
is not specified this data is buffered in memory and is now part of
`form.Value` instead of `form.File` which creates an inconsistent
behavior.
This PR tries to fix this in our code for the time being, but ideal PR
would be to fix the upstream mime/multipart library to handle the
above situation consistently.
Harshavardhana