# emerge -avt1 dev-python/python-exec

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!
[ebuild  N     ] dev-python/python-exec-10000.2:2  PYTHON_TARGETS="(jython2_5) (jython2_7) (pypy) (python2_6) (python2_7) (python3_2) (python3_3) (python3_4)" 0 kB
[ebuild     U *]  dev-lang/python-exec-0.9999 [0.3.1-r1] PYTHON_TARGETS="(jython2_5) (jython2_7) (pypy) (python2_6) (python2_7) (python3_2) (python3_3) (python3_4*)" 0 kB
[ebuild     U *]  dev-lang/python-exec-2.9999:2 [2.0.1-r1:2] PYTHON_TARGETS="(jython2_5) (jython2_7) (pypy) (python2_6) (python2_7) (python3_2) (python3_3) (python3_4*)" 0 kB

Total: 3 packages (2 upgrades, 1 new), Size of downloads: 0 kB

The following keyword changes are necessary to proceed:
 (see "package.accept_keywords" in the portage(5) man page for more details)
# required by dev-python/psycopg-2.5.1
# required by www-apps/trac-1.0.1[postgres]
# required by @selected
# required by @world (argument)
=dev-lang/python-exec-2.9999 **
# required by dev-python/python-exec-10000.2
# required by dev-python/python-exec (argument)
=dev-lang/python-exec-0.9999 **

NOTE: The --autounmask-keep-masks option will prevent emerge
      from creating package.unmask or ** keyword changes.

Use --autounmask-write to write changes to config files (honoring
CONFIG_PROTECT). Carefully examine the list of proposed changes,
paying special attention to mask or keyword changes that may expose
experimental or unstable packages.