eg https://autobuilder.yocto.io/builders/nightly-x86-64/builds/506/steps/Running%20Sanity%20Tests/logs/stdio

NOTE: core-image-sato-sdk-1.0-r0 do_testimage: Target didn't reached login boot in 1500 seconds
NOTE: core-image-sato-sdk-1.0-r0 do_testimage: Last 25 lines of text:

NOTE: core-image-sato-sdk-1.0-r0 do_testimage: Check full boot log: /home/pokybuild/yocto-autobuilder/yocto-worker/nightly-x86-64/build/build/tmp/work/qemux86_64-poky-linux/core-image-sato-sdk/1.0-r0/testimage/qemu_boot_log.20170920163914
WARNING: core-image-sato-sdk-1.0-r0 do_testimage: Qemu ended unexpectedly, dump data from host is in /tmp/oe-saved-tests/201709201704_qemu
NOTE: core-image-sato-sdk-1.0-r0 do_testimage: Stopping logging thread

Note the blank line where the last 25 lines are expected.  However, that log does exist and has content:

$ tail /home/pokybuild/yocto-autobuilder/yocto-worker/nightly-x86-64/build/build/tmp/work/qemux86_64-poky-linux/core-image-sato-sdk/1.0-r0/testimage/qemu_boot_log.20170920163914
[    0.444516] ACPI: PCI Interrupt Link [LNKC] enabled at IRQ 10
[    0.497063] ACPI: PCI Interrupt Link [LNKA] enabled at IRQ 10
[    0.498586] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[    0.523051] 00:05: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[    0.546702] 00:06: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
[    0.548130] Linux agpgart interface v0.103
[    0.548890] random: fast init done
[    0.549439] random: crng init done
[    0.580827] brd: module loaded
[    0.596852] loop: module loaded