swiftclient.service upload leaks filehandles for large files

When uploading large files (i.e. multi-segment ones) using the swiftclient.service functions, if you pass a file path instead of a file object it seems to leave the files open after upload.

For example:
tmpfile = "/tmp/wibble"
obj = SwiftUploadObject(tmpfile, object_name=tmpfile)
swift.upload(container="mycontainer", objects=[obj])

After this, lsof shows /tmp/wibble is still open (multiple times)

This approach works around the problem:
with open(tmpfile, "r") as f:
    obj = SwiftUploadObject(f, object_name=tmpfile)
    swift.upload(container=container, objects=[obj]):

While I've seen this on the wily packaged version, it also appears to be a problem in the upstream (3.0) python module.

$ lsb_release -rd
Description: Ubuntu 15.10
Release: 15.10

$ apt-cache policy python-swiftclient
python-swiftclient:
  Installed: 1:2.6.0-1ubuntu1
  Candidate: 1:2.6.0-1ubuntu1
  Version table:
 *** 1:2.6.0-1ubuntu1 0
        500 http://gb.archive.ubuntu.com/ubuntu/ wily/main amd64 Packages
        100 /var/lib/dpkg/status