objstr: *strip(): If nothing is stripped, don't create dup string.
diff --git a/py/objstr.c b/py/objstr.c
index 42a2464..d095c8b 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -691,6 +691,12 @@
     assert(last_good_char_pos >= first_good_char_pos);
     //+1 to accomodate the last character
     machine_uint_t stripped_len = last_good_char_pos - first_good_char_pos + 1;
+    if (stripped_len == orig_str_len) {
+        // If nothing was stripped, don't bother to dup original string
+        // TODO: watch out for this case when we'll get to bytearray.strip()
+        assert(first_good_char_pos == 0);
+        return args[0];
+    }
     return mp_obj_new_str_of_type(self_type, orig_str + first_good_char_pos, stripped_len);
 }