`make htmlhelp` always exits with error code 1
Even if there is no error no warnings produced `make htmkhelp` exits with error code 1, and this breaks the build process, where sphinx is the part of it.
C:\work\Bazaar\bzr-2a\2.3\doc\en>call make htmlhelp Running Sphinx v1.0.7 loading pickled environment... done building [htmlhelp]: targets for 0 source files that are out of date updating environment: 0 added, 0 changed, 0 removed looking for now-outdated files... none found no targets are out of date.
Build finished; now you can run HTML Help Workshop with the .hhp project file in _build/htmlhelp.
C:\work\Bazaar\bzr-2a\2.3\doc\en>echo %ERRORLEVEL% 1