Fix two node-copying bugs in update

PrintMutation.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "VersionedMap.h"
+#include <ctype.h>
 #include <inttypes.h>
 #include <stdio.h>
 
@@ -10,22 +11,42 @@ printMutation(const weaselab::VersionedMap::Iterator::VersionedMutation &m) {
   case weaselab::VersionedMap::Set:
     printf("set ");
     for (int i = 0; i < m.param1Len; ++i) {
-      printf("x%02x", m.param1[i]);
+      auto c = m.param1[i];
+      if (isprint(c)) {
+        printf("%c", c);
+      } else {
+        printf("x%02x", c);
+      }
     }
     printf(" -> '");
     for (int i = 0; i < m.param2Len; ++i) {
-      printf("x%02x", m.param2[i]);
+      auto c = m.param2[i];
+      if (isprint(c)) {
+        printf("%c", c);
+      } else {
+        printf("x%02x", c);
+      }
     }
     printf("' @ %" PRId64 "\n", m.version);
     break;
   case weaselab::VersionedMap::Clear:
     printf("clear [");
     for (int i = 0; i < m.param1Len; ++i) {
-      printf("x%02x", m.param1[i]);
+      auto c = m.param1[i];
+      if (isprint(c)) {
+        printf("%c", c);
+      } else {
+        printf("x%02x", c);
+      }
     }
     printf(", ");
     for (int i = 0; i < m.param2Len; ++i) {
-      printf("x%02x", m.param2[i]);
+      auto c = m.param2[i];
+      if (isprint(c)) {
+        printf("%c", c);
+      } else {
+        printf("x%02x", c);
+      }
     }
     printf(") @ %" PRId64 "\n", m.version);
     break;