Vivek Khera (newline fixes by me, removed part

r1912002 | dsahlberg | 2023-08-29 19:55:03 +0000 (Tue, 29 Aug 2023)

Fix issue #4621

The svn command line client version 1.9 and later will return
an error on propget if the property doesn't exist.

* contrib/client-side/svn_load_dirs/svn_load_dirs.pl.in
  Check for the property existence using proplist before trying
  to get the property

Patch by: Vivek Khera (newline fixes by me, removed part
already fixed in r1863392)