skiboot 6.0.7 was released on Friday August 3rd, 2018. It replaces skiboot-6.0.6 as the current stable release in the 6.0.x series.
It is recommended that 6.0.7 be used instead of any previous 6.0.x version due to it containing a workaround for hardware errata in the XIVE interrupt controller (present on POWER9 systems).
The bug fix is:
xive: Disable block tracker
Due to some HW errata, the block tracking facility (performance optimisation for large systems) should be disabled on Nimbus chips. Disable it unconditionally for now.