Building Haddock documentation panics with perf build on x86_64 Linux

After setting BuildFlavor = perf in build.mk compilation ends with a panic:

"/home/luite/buildtest/ghc-clean-buildtest/ghc/inplace/bin/haddock" --odir="libraries/ghc-prim/dist-install/doc/html/ghc-prim" --no-tmp-comp-dir --dump-interface=libraries/ghc-prim/dist-install/doc/html/ghc-prim/ghc-prim.haddock --html --hoogle --title="ghc-prim-0.3.1.0: GHC primitives" --prologue="libraries/ghc-prim/dist-install/haddock-prologue.txt"   --optghc=-hisuf --optghc=dyn_hi --optghc=-osuf --optghc=dyn_o --optghc=-hcsuf --optghc=dyn_hc --optghc=-fPIC --optghc=-dynamic --optghc=-H32m --optghc=-O --optghc=-package-name --optghc=ghc-prim-0.3.1.0 --optghc=-hide-all-packages --optghc=-i --optghc=-ilibraries/ghc-prim/. --optghc=-ilibraries/ghc-prim/dist-install/build --optghc=-ilibraries/ghc-prim/dist-install/build/autogen --optghc=-Ilibraries/ghc-prim/dist-install/build --optghc=-Ilibraries/ghc-prim/dist-install/build/autogen --optghc=-Ilibraries/ghc-prim/. --optghc=-optP-include --optghc=-optPlibraries/ghc-prim/dist-install/build/autogen/cabal_macros.h --optghc=-package --optghc=rts-1.0 --optghc=-package-name --optghc=ghc-prim --optghc=-XHaskell98 --optghc=-XCPP --optghc=-XMagicHash --optghc=-XForeignFunctionInterface --optghc=-XUnliftedFFITypes --optghc=-XUnboxedTuples --optghc=-XEmptyDataDecls --optghc=-XNoImplicitPrelude --optghc=-O2 --optghc=-no-user-package-db --optghc=-rtsopts --optghc=-odir --optghc=libraries/ghc-prim/dist-install/build --optghc=-hidir --optghc=libraries/ghc-prim/dist-install/build --optghc=-stubdir --optghc=libraries/ghc-prim/dist-install/build --source-module=src/%{MODULE/./-}.html --source-entity=src/%{MODULE/./-}.html#%{NAME}   libraries/ghc-prim/./GHC/Classes.hs  libraries/ghc-prim/./GHC/CString.hs  libraries/ghc-prim/./GHC/Debug.hs  libraries/ghc-prim/./GHC/Magic.hs  libraries/ghc-prim/dist-install/build/GHC/PrimopWrappers.hs  libraries/ghc-prim/./GHC/PrimWrappers.hs  libraries/ghc-prim/./GHC/IntWord64.hs  libraries/ghc-prim/./GHC/Tuple.hs  libraries/ghc-prim/./GHC/Types.hs libraries/ghc-prim/dist-install/build/autogen/GHC/Prim.hs +RTS -tlibraries/ghc-prim/dist-install/doc/html/ghc-prim/ghc-prim.haddock.t --machine-readable
Haddock coverage:
 100% (  1 /  1) in 'GHC.IntWord64'
  78% (  7 /  9) in 'GHC.Types'
   3% (  2 / 63) in 'GHC.Tuple'
   0% (  0 /  3) in 'GHC.Debug'
   0% (  0 /351) in 'GHC.PrimopWrappers'
   2% (  1 / 43) in 'GHC.PrimWrappers'
  17% (  1 /  6) in 'GHC.CString'
  31% (170 /540) in 'GHC.Prim'
 100% (  3 /  3) in 'GHC.Magic'
  38% (  6 / 16) in 'GHC.Classes'
haddock: internal error: haddock: panic! (the 'impossible' happened)
  (GHC version 7.7.20130912 for x86_64-unknown-linux):
	Static flags have not been initialised!
        Please call GHC.newSession or GHC.parseStaticFlags early enough.

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

make[1]: *** [libraries/ghc-prim/dist-install/doc/html/ghc-prim/ghc-prim.haddock] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [all] Error 2

I've seen this problem before, but I thought that it was related to my patch. Now I got it on master branch and Luite reported the same problem on #ghc (log above is actually his).

A workaround for this is disabling building of documentation in "perf" section of build.mk.