dirstate-item: ignore mtime to write v1 when `mtime-second-ambiguous` is set

We cannot preserve that information in the v1 format so that mtime is ambiguous.

Differential Revision: https://phab.mercurial-scm.org/D11844

mercurial/cext/parsers.c

@@ -269,7 +269,8 b' static inline int dirstate_item_c_v1_mti'
 	} else if (!(self->flags & dirstate_flag_has_mtime) ||
 	           !(self->flags & dirstate_flag_p1_tracked) ||
 	           !(self->flags & dirstate_flag_wc_tracked) ||
-	           (self->flags & dirstate_flag_p2_info)) {
+	           (self->flags & dirstate_flag_p2_info) ||
+	           (self->flags & dirstate_flag_mtime_second_ambiguous)) {
 		return ambiguous_time;
 	} else {
 		return self->mtime_s;

mercurial/pure/parsers.py

@@ -551,6 +551,8 b' class DirstateItem(object):'
             return AMBIGUOUS_TIME
         elif not self._p1_tracked:
             return AMBIGUOUS_TIME
+        elif self._mtime_second_ambiguous:
+            return AMBIGUOUS_TIME
         else:
             return self._mtime_s
 

rust/hg-core/src/dirstate/entry.rs

@@ -454,7 +454,11 b' impl DirstateEntry {'
         } else if !self.flags.contains(Flags::P1_TRACKED) {
             MTIME_UNSET
         } else if let Some(mtime) = self.mtime {
-            i32::try_from(mtime.truncated_seconds()).unwrap()
+            if mtime.second_ambiguous {
+                MTIME_UNSET
+            } else {
+                i32::try_from(mtime.truncated_seconds()).unwrap()
+            }
         } else {
             MTIME_UNSET
         }