Fedora distribution refuses shebang with unknown python version:
ERROR: ambiguous python shebang in /opt/slapos/tmp-networkcached/bin/networkcache-download: #!/usr/bin/python. Change it to python3 (or python2) explicitly.
ERROR: ambiguous python shebang in /opt/slapos/tmp-networkcached/bin/networkcache-upload: #!/usr/bin/python. Change it to python3 (or python2) explicitly.
ERROR: ambiguous python shebang in /opt/slapos/tmp-networkcached/bin/buildout: #!/usr/bin/python. Change it to python3 (or python2) explicitly.
ERROR: ambiguous python shebang in /opt/slapos/tmp-networkcached/bin/generate-signature-key: #!/usr/bin/python. Change it to python3 (or python2) explicitly.

Using python2.7 explicitely will make the shebang /usr/bin/python2.7