Merged from trunk -r12165:12168

   Merged from trunk -r12165:12168

   | 12166   | Validate $ROOT inside the --resume merge list in order to    |
   | zmedico | avoid a pottential KeyError due to a stale merge list that   |
   |         | was for a different $ROOT setting. Thanks to Ned Ludd        |
   |         | <solar@g.o> for reporting.                                   |

   | 12168   | Add docs for PORTAGE_GPG_DIR and PORTAGE_GPG_KEY that are    |
   | zmedico | used by repoman for FEATURES=sign support. Thanks to Petteri |
   |         | Räty <betelgeuse@g.o> for reporting.                        |

svn path=/main/branches/prefix/; revision=12172