File size decreases when synchronizing folders with a sftp account using lftp.

Issue

• File size decreases when synchronizing folders with a sftp account using lftp.

• It's reproducible by following the steps below:

# lftp -e "mirror -e -vvv sftp://<USERNAME>:<PASSWD>@<SRCHOST>/<SRC PATH>/ sfftp://<USERNAME>:<PASSWD>@<DESTHOST>/<DEST PATH>/"

1. 800 files exist in <SRC PATH>.
2. <DEST PATH> is empty. 
3. Run above mentioned command (lftp -e ~~~) to synchronize the 2 folders, <SRC PATH> and <DEST PATH>.
4. Issue occurs. File size decreases on the below listed 10 image files of total files (800 files in total) as shown below:

+----------+---------------+--------------------+-----------+
| File     | Original size | Mirrored file size | File type |
+----------+---------------+--------------------+-----------+
|        A |    108,971    |      98,304        |   .png    |
|        B |    110,294    |      98,304        |   .jpg    |
|        C |    127,948    |      98,304        |   .png    |
|        D |     99,510    |      98,304        |   .gif    |
|        E |    123,354    |      98,304        |   .jpg    |
|        F |    115,235    |      98,304        |   .jpg    |
|        G |    123,774    |      98,304        |   .jpg    |
|        H |    106,865    |      98,304        |   .jpg    |
|        I |    108,078    |      98,304        |   .jpg    |
|        J |    120,619    |      98,304        |    .js    |
+----------+---------------+--------------------+-----------+

• The issue occurs only when either or is NFS mounted directory.

• Issue does not occur when both and are directories sitting on the local filesystem