For issue #4519, stop removing valid information from the EXTERNALS table when calling 'svn upgrade'
For issue #4519, stop removing valid information from the EXTERNALS table
when calling 'svn upgrade'

* subversion/libsvn_client/upgrade.c
  (upgrade_externals_from_properties): New prototype.
  (svn_client_upgrade): Upgrade properly recorded wc-ng EXTERNALS directly. Only
    if there are none, try to upgrade from svn:externals. Extract this upgrade code
    to a separate function upgrade_externals_from_properties().
  (upgrade_externals_from_properties): New function.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1625533 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion