Merged from trunk -r14852:14876

   Merged from trunk -r14852:14876

   | 14853   | Disable backtracking in the depgraph constructor call when   |
   | zmedico | appropriate.                                                 |

   | 14854   | Bug #293730 - Fix bad || choices triggered in some cases     |
   | zmedico | inside _dep_check_composite_db._visible() when --update is   |
   |         | not enabled.                                                 |

   | 14855   | Fix depgraph._prune_tree_display() to preserve uninstall     |
   | zmedico | tasks. Thanks to Jonathan Callen <abcd@g.o> for reporting.   |

   | 14856   | Fix blocker display to work properly with --tree             |
   | zmedico | --unordered-display.                                         |

   | 14857   | In depgraph._serialize_tasks(), ensure that unsolvable       |
   | zmedico | blockers can't be accidentally marked as satisfied.          |

   | 14858   | Tweak logic from previous commit.                            |
   | zmedico |                                                              |

   | 14859   | Optimized the code for bug #288083 and make it handle more   |
   | zmedico | cases. Now Package instances have 'visible' and 'masks'      |
   |         | attributes, since this information needs to be accessed in   |
   |         | more places now.                                             |

   | 14873   | Bug #293998 - Use OSError.errno instead of trying to         |
   | zmedico | subscript the exception when handling errno.EXDEV in         |
   |         | movefile(), since exceptions do not support subscripting in  |
   |         | python3.                                                     |

   | 14874   | Add "repository" attribute to CategorySet (revert r11597).   |
   | zmedico | Thanks to TGL <tom.gl@free.fr> for this patch, posted on bug |
   |         | #291414.                                                     |

   | 14875   | Bug #293614 - When the backtracking limit is reached and     |
   | zmedico | there is a SLOT conflict to display, hint that a larger      |
   |         | --backtrack value might solve the conflict automatically.    |

   | 14876   | Add a test case which simply compiles all modules, useful    |
   | zmedico | for testing syntax compatibility with the current version of |
   |         | python.                                                      |

svn path=/main/branches/prefix/; revision=14880