Merged revisions 87919 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r87919 | alexander.belopolsky | 2011-01-10 20:21:25 -0500 (Mon, 10 Jan 2011) | 4 lines

  Issue #1726687: time.mktime() will now correctly compute value one
  second before epoch.  Original patch by Peter Wang, reported by Martin
  Blais.
........
diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index 1ebee6f..61c1ccc 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -632,8 +632,11 @@
     time_t tt;
     if (!gettmarg(tup, &buf))
         return NULL;
+    buf.tm_wday = -1;  /* sentinel; original value ignored */
     tt = mktime(&buf);
-    if (tt == (time_t)(-1)) {
+    /* Return value of -1 does not necessarily mean an error, but tm_wday
+     * cannot remain set to -1 if mktime succedded. */
+    if (tt == (time_t)(-1) && buf.tm_wday == -1) {
         PyErr_SetString(PyExc_OverflowError,
                         "mktime argument out of range");
         return NULL;