JDK9 install failure on build-marist-rhel74-s390x-1 (Space?)

[sxa]

TASK [adoptopenjdk9 : Install latest release if one not already installed] *****
15:09:16
fatal: [build-marist-rhel74-s390x-1]: FAILED! => {"changed": false, "failed": true, "msg": "Failure downloading https://api.adoptopenjdk.net/openjdk9/nightly/s390x_linux/latest/binary, [Errno 28] No space left on device"}

Ref: https://ci.adoptopenjdk.net/computer/build-marist-rhel74-s390x-1/

[sxa]

Root FS is indeed full:

[root@build-marist-rhel74-s390x-1 ~]# df -k /
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/dasda2      6061632 5847688         0 100% /

[root@build-marist-rhel74-s390x-1 var]# du -ks *
4	account
4	adm
364880	cache
4	crash

Cleared up by running yum clean all abnd there is 240Mb available. Which isn't a lot and might get blown by installing JDK9 but it's a start ...