This seems to influence also other related scenarios, e.g. "jeos-fs_stress": https://openqa.suse.de/tests/3234280
Investigating the diff in os-autoinst-distri-opensuse narrows it down to:
$ git log1 --no-merges 3867e7f4090d07b7cef403c62b0e641ba3e0a74a..36d965bb233c6b70d68b62f5ab89f2d112069310
35fa34951 Create QAM apache regression test
c11bdb2d8 Add/remove SDK extension only on SLE
f4fd80724 wicked: pre|post logs: Add /etc/resolv.conf
8addd8b76 Firefox_nss: Revert unnecessary x11utils::turn_off_gnome_screensaver call
a701928ba HPC: Update the changelog
9f819b90a HPC: Check if nodes are accessible
1d58498d2 Add 12sp1 support, tweek patching and hotplugging
42c7619e0 wicked: Use offline upload of log files
aa5c5699b Add functions (upload|download)_file()
667cef448 Use VIRTIO_CONSOLE_NUM to add more vconsoles
5a66ad15a HPC: Comprehensive HPC cluster tests
cea6cc606 zypp_lifecycle_toolchain Workaround gcc8 issue
fe86484c1 Add latexdiff test
a6628b319 Enable refactored raid in opensuse
67ed52c99 wicked: Surround test with barriers
775c4fa52 Uninstall conflicting package before install
42833edbb Enlarge check_screen timeout value for module-selection in scc_registration.
eaf7c6fb4 Use zypper_ar() in some tests
d310be7db utils: zypper_ar() enhancements
af2074d0a Add fix for wavpack on sle12sp5
c97589470 HPC: Schedule srun jobs on some compute nodes
5bdc97d6e HPC: Add sleep before srun jobs are scheduled
f1c4edc7e repo_tools: Add add_qa_{head,web}_repo() and use it
969d2b93e zypper_ar: Check repo exists before adding it
fe1116c3a PublicCloud: Add variable timeout for LTP tests
4c0642ea2 bootloader: grub is the loader on Tumbleweed non-32bit livecd
55065ae8d Fix nvidia repo removal in patch_and_reboot
51b8a247a Refactor KOTD installation
5544250fd [virt_autotest] Support guest sles-12-sp5 for virt_v2v test
792887cd0 Fix cups test
dc85b6487 Fix patch_and_reboot on QAM installation tests
96af54f84 Fix power_action issue by add textmode=1
94862696b add yast_tftp_server test
2b394edaf Fix boot on aarch64
80c246bbc Fix the multimachine setup for NFS* QAM scenarios
751b6e25e Add ntp test
21c928eb7 Need confirm Yes for online repos updates in scc_registration for sle12sp4 regression tests
5b836be89 Add description for FUNCTION variable
c9be43f9e Update repos for transactional_server test (poo#53444)
895c583f8 Remove RESOLVED INVALID soft failure
and regarding os-autoinst as the first incomplete happened on 2019-07-16 and last good was on 2019-07-11 it could be an update of packages within that timerange. From openqaworker8 in /var/log/zypper/history:
2019-07-09 11:42:40|install|os-autoinst|4.5.1562413838.c3d5e8ac-131.1|x86_64|root@openqaworker8|openQA|aa6390b18980513f8e77c9b5c313650b2ca82581a3d33ff73e5dff1b5f25de92|
2019-07-09 14:24:09|install|os-autoinst|4.5.1562413838.c3d5e8ac-lp151.131.1|x86_64||openQA|9e3045f495ed5d77aa63153f1b835ecbddcbd1083b304295d383c1934acc63d9|
2019-07-17 14:02:30|install|os-autoinst|4.5.1563188951.f6f7c6b3-lp151.133.1|x86_64|root@openqaworker8|openQA|41bc9a9947b86d8cbcf2a2e869e9812d99508d2a4e6106580de45468c0120e00|
2019-07-24 12:23:29|install|os-autoinst|4.5.1563904797.8d4b96b9-lp151.151.1|x86_64|root@openqaworker8|openQA|47cec3ff573b88ce32d1dac4537abcd5a53fa1efcc26dd080b986846743390bb|
so something in the range c3d5e8ac..f6f7c6b3:
$ git log1 --no-merges c3d5e8ac..f6f7c6b3
b57dc9ed (okurz/feature/devel) spec: Provide a "devel" subpackage pulling in all build+test dependencies
ff9b6377 spec: Fix warning about missing explicit perl-base
unlikely to be related so I rather suspect the test changes.