This page tracks porting progress of Python 3. The epic covering the initial port was 

PackageJIRAOwner
base
pex_exceptions
utils
pex_policy
daf_base
pex_logging
pex_config
log
ndarray
daf_persistence
afw
skymap
geom
daf_butlerUtils
psfexDone, no python source
obs_test
shapelet
skypix
pipe_base
db

cat
mysqlpython
display_ds9
coadd_utils
ctrl_events
ctrl_pool
ctrl_orca
ctrl_provenance
ctrl_stats
ctrl_execute
ctrl_platform_lsst
ctrl_platform_gordon
pykg_config
meas_base
meas_algorithms
meas_extensions_photometryKron
meas_extensions_simpleShape
meas_extensions_psfex
meas_deblender
meas_extensions_shapeHSM
meas_extensions_ngmix
meas_astrom
meas_modelfit
pipe_tasks
pipe_supertask
coadd_chisquared
esutil
scisql
astrometry_net
ip_isr
ip_diffim
datarel

obs_lsstSim
obs_subaru
obs_decam
obs_sdss
obs_cfht
ci_hsc
validate_drp

lmfit
ngmix
sphgeom
Qserv

obs_monocam
dax_dbserv

dax_imgserv

dax_metaserv

dax_webserv

dax_webservcommon

pipe_drivers
Russell Owen
daf_ingest