I have set PYTHON_TARGETS="python3_5 python2_7" in my make.conf, but have not set any PYTHON_SINGLE_TARGET. This works fine for all packages except lensfun: They automatically set PYTHON_SINGLE_TARGET to python2_7 or 3_5. However, with these settins, emerge gives an error for lensfun: !!! The ebuild selected to satisfy ">=media-libs/lensfun-0.2.5" has unmet requirements. - media-libs/lensfun-0.3.2::gentoo USE="-doc -test" CPU_FLAGS_X86="sse sse2" PYTHON_SINGLE_TARGET="python3_4 -python3_3 -python3_5" PYTHON_TARGETS="python3_5 -python3_3 -python3_4" The following REQUIRED_USE flag constraints are unsatisfied: python_single_target_python3_4? ( python_targets_python3_4 ) The above constraints are a subset of the following complete expression: exactly-one-of ( python_single_target_python3_3 python_single_target_python3_4 python_single_target_python3_5 ) python_single_target_python3_3? ( python_targets_python3_3 ) python_single_target_python3_4? ( python_targets_python3_4 ) python_single_target_python3_5? ( python_targets_python3_5 ) The problem is that it uses PYTHON_TARGETS=python3_5 (and not 3_4) as set by make.conf, but auto-selects PYTHON_SINGLE_TARGET=python3_4 instead of 3_5. With "media-libs/lensfun -python_single_target_python3_4 python_single_target_python3_5" in package.use, emerge works fine, but this workaround should not be needed.
*** This bug has been marked as a duplicate of bug 472932 ***
