Fix intermittent failures when "svn add" guesses a near-empty file is binary and hence
the output is different.

--- subversion-1.14.1/subversion/tests/cmdline/svntest/main.py.testnoautoprops
+++ subversion-1.14.1/subversion/tests/cmdline/svntest/main.py
@@ -691,6 +691,7 @@
 
 [miscellany]
 interactive-conflicts = false
+enable-magic-file = no
 """
     if exclusive_wc_locks:
       config_contents += """