Improve the detection of whether a node can be created at a given path.
Improve the detection of whether a node can be created at a given path.

Specifically, if the path represents a child from an ancestor's copy,
move, or rotate, then we should allow further changes to that child.
Since the child is uncommitted, the REPLACES_REV will be
SVN_INVALID_REVNUM.

* subversion/libsvn_fs/editor.c:
  (can_create): update docstring. add ancestor checks for *-here ops.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion