Hadrian: Suddenly a full build fails with: Rules may not be recursive

[Roland Senn]

Hi,

Suddenly I'm unable to build! As usual, I did:

git pull upstream master --recurse-submodules=yes
git submodule update --init --recursive


$ hadrian/build.sh clean
Up to date
| Removing Hadrian files...
| Remove directory _build/stage0
| Remove directory _build/stage1
| Remove directory _build/stage2
| Remove directory _build/stage3
| Remove directory sdistprep
| Remove directory _build (after build completes)
| Done.

... + statistics

$ hadrian/build.sh -c --flavour=devel2 -j2
Up to date
| Running boot...
Error when running Shake build system:
  at action, called at src/Rules.hs:68:19 in main:Rules
  at apply1, called at
src/Development/Shake/Internal/Rules/Oracle.hs:159:32 in shake-0.18.2-
fca156899176fbf7a9b05f30b3ec991784b3e60af38a503ea1cb277fd96f971e:Develo
pment.Shake.Internal.Rules.Oracle
* Depends on: OracleQ (KeyValue ("hadrian/cfg/system.config","host-
os"))
  at need, called at src/Hadrian/Oracles/TextFile.hs:90:9 in
main:Hadrian.Oracles.TextFile
* Depends on: hadrian/cfg/system.config
  at &%>, called at src/Rules/Configure.hs:21:5 in main:Rules.Configure
* Depends on: hadrian/cfg/system.config mk/config.h compiler/ghc.cabal
rts/rts.cabal
  at apply1, called at
src/Development/Shake/Internal/Rules/Oracle.hs:159:32 in shake-0.18.2-
fca156899176fbf7a9b05f30b3ec991784b3e60af38a503ea1cb277fd96f971e:Develo
pment.Shake.Internal.Rules.Oracle
* Depends on: OracleQ (KeyValue ("hadrian/cfg/system.config","host-
os"))
* Raised the exception:
Build system error - recursion detected:
  Key type:   OracleQ KeyValue
  Key value:  OracleQ (KeyValue ("hadrian/cfg/system.config","host-
os"))
Rules may not be recursive


OS is Linux Debian 9 (x86_64)

Any ideas what's wrong??

Many thanks and kind regards
   Roland