Test KVM AHK: "Assertion failed: !current->Dirty" at "ntoskrnl/cc/view.c, line 459", after new Cc lazy writer

reactos-bootcdregtest-0.4.8-dev-912-g2d69520-x86-gcc-lin-dbg.iso

1. Downloaded this ISO.
2. 1st attempt at installing it. (On VPC 2004 + 128MiB.)

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Stage 1 completed, reboot, crash:

...

(dll/win32/userenv/profile.c:771) Error: 2

err:(base/services/wkssvc/rpcserver.c:61) RpcServerListen() failed (Status 6b1)

err:(base/services/srvsvc/rpcserver.c:64) RpcServerListen() failed (Status 6b1)

*** Assertion failed: !current->Dirty

***   Source File: /srv/buildbot/Build_GCCLin_x86/build/ntoskrnl/cc/view.c, line 461

Break repeatedly, break Once, Ignore, terminate Process or terminate Thread (boipt)? 

kdb:>

NB: My keyboard doesn't work, so no "bt".

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Clues which may (not) apply:

Previous build I used, without issues was:
reactos-bootcdregtest-0.4.8-dev-867-g5c52ae6-x86-gcc-lin-dbg.iso + 256MiB

During 048-912 stage 1, it felt like there were 1+ second pauses (= no disk activity) during file copy.
Not sure whether that was a wrong feeling, usual, newly expected, or a possible regression.