Can't build Sphinx HTML docs on GHC HEAD

Attempting to build the Sphinx HTML documentation (i.e., putting BUILD_SPHINX_HTML = YES in one's mk/build.mk file) using the latest GHC HEAD (commit 3910d3e2) immediately fails:

$ make
===--- building phase 0
make --no-print-directory -f ghc.mk phase=0 phase_0_builds
make[1]: Nothing to be done for `phase_0_builds'.
===--- building phase 1
make --no-print-directory -f ghc.mk phase=1 phase_1_builds
make[1]: Nothing to be done for `phase_1_builds'.
===--- building final phase
make --no-print-directory -f ghc.mk phase=final all
/usr/bin/sphinx-build -b html -d docs/users_guide/.doctrees-html -D latex_paper_size=letter docs/users_guide docs/users_guide/build-html/users_guide
Running Sphinx v1.2.2

Exception occurred:
  File "conf.py", line 29, in <module>
    """.format(llvm_version=ghc_config.llvm_version)
AttributeError: 'module' object has no attribute 'llvm_version'
The full traceback has been saved in /tmp/sphinx-err-DVajkq.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://bitbucket.org/birkenfeld/sphinx/issues/>. Thanks!
make[1]: *** [docs/users_guide/build-html/users_guide/index.html] Error 1
make: *** [all] Error 2

Trac metadata

Trac field	Value
Version	8.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Documentation
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