Зачем emerge всё это делает каждый раз?

...
These are the packages that would be merged, in order:
Calculating dependencies | * A file is not listed in the Manifest: '/repo/gentoo/dev-lang/python/python-2.6.8-r3.ebuild'
 | * ERROR: virtual/python-argparse-1::gentoo failed (depend phase):
 *   No supported implementations match python_gen_usedep patterns: python2_6
 * 
 * Call stack:
 *                  ebuild.sh, line 545:  Called source '/repo/gentoo/virtual/python-argparse/python-argparse-1.ebuild'
 *   python-argparse-1.ebuild, line  19:  Called python_gen_cond_dep 'dev-python/argparse[${PYTHON_USEDEP}]' 'python2_6'
 *           python-r1.eclass, line 373:  Called python_gen_usedep 'python2_6'
 *           python-r1.eclass, line 293:  Called die
 * The specific snippet of code:
 \ *    [[ ${matches[@]} ]] || die "No supported implementations match python_gen_usedep patterns: ${@}"
 * 
 * If you need support, post the output of `emerge --info '=virtual/python-argparse-1::gentoo'`,
 * the complete build log and the output of `emerge -pqv '=virtual/python-argparse-1::gentoo'`.
 * Working directory: '/usr/lib64/portage/pym'
 * S: '/var/tmp/portage/virtual/python-argparse-1/work/python-argparse-1'
 / * ERROR: virtual/python-argparse-1::gentoo failed (depend phase):
 *   No supported implementations match python_gen_usedep patterns: python2_6
 * 
 * Call stack:
 *                  ebuild.sh, line 545:  Called source '/repo/gentoo/virtual/python-argparse/python-argparse-1.ebuild'
 *   python-argparse-1.ebuild, line  19:  Called python_gen_cond_dep 'dev-python/argparse[${PYTHON_USEDEP}]' 'python2_6'
 *           python-r1.eclass, line 373:  Called python_gen_usedep 'python2_6'
 *           python-r1.eclass, line 293:  Called die
 * The specific snippet of code:
 *      [[ ${matches[@]} ]] || die "No supported implementations match python_gen_usedep patterns: ${@}"
 * 
 * If you need support, post the output of `emerge --info '=virtual/python-argparse-1::gentoo'`,
 * the complete build log and the output of `emerge -pqv '=virtual/python-argparse-1::gentoo'`.
 * Working directory: '/usr/lib64/portage/pym'
 * S: '/var/tmp/portage/virtual/python-argparse-1/work/python-argparse-1'
... done!
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