Merged from trunk -r12146:12161

   Merged from trunk -r12146:12161

   | 12148   | Bug #249185 - For common cases in which USE deps trigger     |
   | zmedico | SLOT conflicts, give a short explanation and suggest a       |
   |         | course of action to solve the problem.                       |

   | 12150   | Make sure depgraph._slot_conflict_explanation() doesn't      |
   | zmedico | display the same atom more than once.                        |

   | 12152   | Bug #249805 - Add some more                                  |
   | zmedico | PreservedLibsRegistry.pruneNonExisting() calls, to avoid a   |
   |         | KeyError from LinkageMap.findConsumers() triggered inside    |
   |         | display_preserved_libs().                                    |

   | 12153   | Enable FEATURES=fixpackages by default since the performance |
   | zmedico | is pretty reasonable now. Thanks to Jeremy Olexa             |
   |         | <darkside@g.o> for the suggestion.                           |

   | 12154   | Sync with 2.1.6 branch.                                      |
   | zmedico |                                                              |

   | 12155   | FEATURES=fixpackages is now enabled by default               |
   | zmedico |                                                              |

   | 12157   | Make fixpackages less noisy by only generting '*' characters |
   | zmedico | for packages that are modified by updates.                   |

   | 12159   | Make fixpackages use a new "#" symbol for /var/db updates    |
   | zmedico | (previously '*' which means 'binary update' was used).       |

svn path=/main/branches/prefix/; revision=12164