New experimental feature SHUTDOWN DEFRAG.

h2/src/main/org/h2/store/PageStore.java

@@ -623,6 +623,7 @@ public class PageStore implements CacheWriter {
             }
             free(a);
         }
+        if (free != b) {
             if (isUsed(b)) {
                 Page pageB = getPage(b);
                 if (pageB != null) {
@@ -638,6 +639,7 @@ public class PageStore implements CacheWriter {
                 free(free);
             }
         }
+    }
 
     private boolean compact(int full, int free) {
         if (full < MIN_PAGE_COUNT || free == -1 || free >= full || !isUsed(full)) {