fast path was not actually fast

Author: Robert Schmidtke

pandas/_libs/src/vendored/numpy/datetime/np_datetime.c

@@ -340,19 +340,9 @@ PyObject *extract_utc_offset(PyObject *obj) {
 
 static int scaleAndOffset(int64_t timestamp, int64_t scale, int64_t offset,
                           int64_t *result) {
-  if (timestamp >= 0) {
-    // fast path for positive timestamps
-    if (checked_int64_mul(timestamp, scale, result) != 0) {
-      return 1;
-    }
-
-    return checked_int64_add(*result, offset, result);
-  }
-
   // for negative timestamps, scaling could overflow
   // even if the scaled and offset timestamp is valid
-  const int overflow = checked_int64_mul(timestamp, scale, result);
-  if (overflow != 0) {
+  if (checked_int64_mul(timestamp, scale, result) != 0) {
     // given the current scale, this is the smallest supported timestamp
     const int64_t min_scalable_timestamp = (NPY_MIN_INT64 + 1) / scale;