GNU build: perf the change only once

util/build-gnu.sh

@@ -134,8 +134,6 @@ else
     # Use a better diff
     sed -i 's|diff -c|diff -u|g' tests/Coreutils.pm
     "${MAKE}" -j "$("${NPROC}")"
-    touch gnu-built
-fi
 
     # Handle generated factor tests
     t_first=00
@@ -172,13 +170,15 @@ for i in ${seq}; do
         sed -i -e "s/\$(tf)\/t${i}.sh//g" Makefile
     done
 
-grep -rl 'path_prepend_' tests/* | xargs sed -i 's| path_prepend_ ./src||'
-
     # Remove tests checking for --version & --help
     # Not really interesting for us and logs are too big
     sed -i -e '/tests\/help\/help-version.sh/ D' \
         -e '/tests\/help\/help-version-getopt.sh/ D' \
         Makefile
+    touch gnu-built
+fi
+
+grep -rl 'path_prepend_' tests/* | xargs sed -i 's| path_prepend_ ./src||'
 
 # printf doesn't limit the values used in its arg, so this produced ~2GB of output
 sed -i '/INT_OFLOW/ D' tests/printf/printf.sh