add an existence test for the .svn directory

source/texk/web2c/luatexdir/getluatexsvnversion.sh

@@ -10,7 +10,7 @@ fi
 FILE="source/texk/web2c/luatexdir/luatex_svnversion.h"
 
 LANG=C
-if [[ -x `which svnversion` ]]
+if [[ -x `which svnversion` && -d ./.svn ]]
 then
   svn up > /dev/null
   svnversion | sed -ne "s/^\([0-9]*\).*$/\#define luatex_svn_revision \1/p" > $FILE