Since this Bug only appears if the file is copied from a CIFS-Share it
now was seen that the error depends on the used SMB-Version. If the
share is mounted with the option vers=2.0, small files can be copied
without blocking. If a higher SMB-Version than 2.0 is used to mount the
share, e.g. vers=2.1 or vers=3.0, the copy fails as described above.
Capturing the network traffic with wireshark shows that the file is
copied completely in both cases, but when the share is mounted in
SMB-Version 2.1 the last 'Read Response' which contains all the data of
the small file never stopps. The 'Close Request' and the 'Close
Response' for the file do not come up until the hanging process is
interrupted. Another difference betweent the Versions is that the 'Read
Request' has 'Len:65536' in SMB-Version 2.1 and 'Len:4096' in
SMB-Version 2.0. The 'Read Response' containing the data in both cases
has the same size.
