Merged from trunk -r13839:13846

   Merged from trunk -r13839:13846

   | 13840   | Use a lazy reference to sys.stdout, in case the API consumer |
   | zmedico | has temporarily overridden stdout.                           |

   | 13841   | Move mtimedb resume list code from action_build() to         |
   | zmedico | Scheduler._save_resume_list().                               |

   | 13842   | Skip Blocker instances inside _add_prefetchers().            |
   | zmedico |                                                              |

   | 13843   | Remove empty log files inside dblink.unmerge(). Thanks to    |
   | zmedico | Diego Pettenò <flameeyes@gentoo.org> for reporting.         |

   | 13844   | FEATURES=unmerge-logs Keep logs from successful unmerge      |
   | zmedico | phases. This is relevant only when PORT_LOGDIR is set.       |
   |         | Thanks to Diego Pettenò <flameeyes@gentoo.org> for the      |
   |         | suggestion.                                                  |

   | 13845   | Always pass encodings='utf_8' to codecs.open(), since        |
   | zmedico | otherwise it can return non-unicode strings (at least in     |
   |         | some cases, observed with python-2.6.2). Don't use unicode   |
   |         | in portage.util.getconfig() for now, since shlex doesn't     |
   |         | seem to support it (spurious \0 characters). If we use       |
   |         | unicode for config variables, it breaks shlex.split() calls  |
   |         | on those variables due to the same issue (spurious \0        |
   |         | characters).                                                 |

   | 13846   | Add comment in calc_depclean() about topological sort        |
   | zmedico | optimization that minimizes issues with implicit deps.       |

svn path=/main/branches/prefix/; revision=13848