Fix a snafu that prevented the optimized code path to be executed in most
cases. This affects legacy txdelta v1 data only - which is quite rare to
find these days.

* subversion/libsvn_delta/text_delta.c
  (patterning_copy): there will be no overlap past the END ..


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1485480 13f79535-47bb-0310-9956-ffa450edef68