Etag generation in swift3 does not match AWS S3

I have a report that the etag computation in swift3 does not match the
one in Amazon S3:

* AWS S3 returns MD5(hex(toUpper(MD5_part_1||...||MD5_part_n)))
  concatenated to "-N" where N is the number of parts
* swift3 instead returns MD5(MD5_part_1||...||MD5_part_n)

For the etags of two parts: f4268b057129ad6eb16a861448c47be1
ae611f5328ee26e0f3707e21b6046bee AWS S3 returns
8dfd4f6217c47b1d587f081ac9a66d87-2 as the etag of the complete
multipart upload response. 8dfd4f6217c47b1d587f081ac9a66d87 can be
computed as:

echo 'f4268b057129ad6eb16a861448c47be1ae611f5328ee26e0f3707e21b6046bee' | xxd -r -p | md5sum

For the etags of two parts: 1672170d6afd306c4c677df44cfbcb60 and
2a1e3a9c4ec7fe84bb61b6418c51f39b swift3 returns
850b7e0ddbbf389d993456a3ffbb2d54 as the etag of the complete multipart
upload response. Aside from the fact that there is no "-N" suffix,
850b7e0ddbbf389d993456a3ffbb2d54 cannot be computed with the same
invocation as before, but it has to be computed as:

echo -n '1672170d6afd306c4c677df44cfbcb602a1e3a9c4ec7fe84bb61b6418c51f39b' | md5sum

The etag generation in swift3 should be changed to match the one in
AWS S3.