Merged from trunk -r13139:13144

   Merged from trunk -r13139:13144

   | 13140   | Fix argument validation to allow file paths. Thanks to       |
   | zmedico | Arfrever for reporting.                                      |

   | 13141   | Add a temporary workaround for bug #263081 (partially        |
   | zmedico | reverts r12757).                                             |

   | 13142   | Remove pointless usage of xrange(). Thanks to Douglass       |
   | zmedico | Anderson <dja@gendja.com> for this patch.                    |

   | 13143   | Inside config.environ(), skip stat call on $T/environment    |
   | zmedico | for phases such as 'clean' and 'depend' where environment    |
   |         | filtering isn't needed. Thanks to Piotr Jaroszyński         |
   |         | <peper@g.o> for reporting.                                   |

   | 13144   | Inside spawn(), avoid redundant os.access() and stat() calls |
   | zmedico | on commonly spawned binaries such as BASH_BINARY,            |
   |         | SANDBOX_BINARY, and FAKEROOT_BINARY. Thanks to Piotr         |
   |         | Jaroszyński <peper@g.o> for reporting.                      |

svn path=/main/branches/prefix/; revision=13191