portability awk add space between -v and it's argument, if anything has changed add ./COPYRIGHT

util/recent_changes.sh

@@ -22,8 +22,10 @@
 # current one is seen.  Used by merge_copyrights.
 
 thisyear=`date +%Y`
-git whatchanged --pretty="date %ai" --date=iso8601 | awk -vre="${thisyear}-" '
+git whatchanged --pretty="date %ai" --date=iso8601 | awk -v re="${thisyear}-" '
+    BEGIN { change=0 }
     $1 == "date" && $2 !~ re { exit(0); }
     $1 == "date" { next; }
     NF == 0 { next; }
-    $(NF-1) ~ /[AM]/ { print "./" $NF }' | sort | uniq
+    $(NF-1) ~ /[AM]/ { print "./" $NF; change=1 }
+    END { if (change) print "./COPYRIGHT" } ' | sort | uniq