When I try to upload new sources to the lookaside cache "fedpkg new-sources" fails
with the following error:

[ralph@lap cryptobone]$ fedpkg -d -v new-sources cryptobone-1.1.1-2.fc25.tar.gz
Creating repo object from /x/fedora/SCM/cryptobone
Could not execute new_sources: (77, '')
Traceback (most recent call last):
File "/usr/bin/fedpkg", line 16, in
main()
File "/usr/lib/python2.7/site-packages/fedpkg/main.py", line 77, in main
sys.exit(client.args.command())
File "/usr/lib/python2.7/site-packages/pyrpkg/cli.py", line 1273, in new_sources
self.cmd.upload(self.args.files, replace=self.args.replace)
File "/usr/lib/python2.7/site-packages/pyrpkg/init.py", line 2368, in upload
self.lookasidecache.upload(self.module_name, f, file_hash)
File "/usr/lib/python2.7/site-packages/pyrpkg/lookaside.py", line 263, in upload
if self.remote_file_exists(name, filename, hash):
File "/usr/lib/python2.7/site-packages/pyrpkg/lookaside.py", line 230, in remote_file_exists
raise UploadError(e)
pyrpkg.errors.UploadError: (77, '')

This is a new file, so it definitely does NOT exist in lookaside cache.

Attached is a strace of the dommand above: