Sync with upstream

Sync with upstream

* svnrdump@1033555:
  load_editor: Call close_directory() on the root directory baton
  svnrdump: Disable debugging output to fix test on Windows.

* tests@1033646:
  srcdir should not be overridden
  svntest/main.py: Fix Windows command-line argument quoting
  load_editor: Call close_directory() on the root directory baton
  svntest/main.py: Introduce default_num_threads constant
  Allow tests to be run without srcdir set again
  Allow tests to be run without exiting
  svntest/sandbox.py: Interpret paths relative to sbox.wc_dir, not cwd
  svntest/sandbox.py: Remove URL support in simple_rm and simple_mkdir
  Treat ./svnrdump_tests.py -- -1 as a request to run the last test
  svntest/tree.py: always check for presence or absence of tree conflicts
  svnrdump_tests.py: only_trunk_A_with_changes_dump passes on Windows.
  svnrdump_tests.py: only_trunk_A_with_changes_dump fails on Windows.