metacat errors out with symbolic link to python on data2

[mamelara]

When attempting to build the new images for metacat on data2, the docker build errors out with this message:

Step 23/31 : RUN ln -s /usr/bin/python3 /usr/bin/python  # symbolic link to python
 ---> Running in a57f6a9619ff
ln: failed to create symbolic link '/usr/bin/python': File exists
The command '/bin/sh -c ln -s /usr/bin/python3 /usr/bin/python  # symbolic link to python' returned a non-zero code: 1

This seems to only happen on data2.ess-dive.lbl.gov. This needs to be investigated.