Fix GncDateEntry date parsing oddities.

The intent was always to default to today if the input string isn't
parsable, but two problems prevented that: First,
qof_scan_date_internal didn't check the return value of strptime and
return FALSE if it failed and second gnc_date_edit_get_date_internal
would unnecessarily munge a valid struct tm from gnc_tm_get_today_neutral.

gnucash/gnome-utils/gnc-date-edit.c

@@ -800,9 +800,6 @@ date_focus_out_event(GtkWidget *widget, GdkEventKey *event, gpointer data)
     tm = gnc_date_edit_get_date_internal (gde);
     gnc_date_edit_set_time (gde, gnc_mktime (&tm));
 
-    /* Get the date again in case it was invalid the first time. */
-    tm = gnc_date_edit_get_date_internal (gde);
-
     g_signal_emit (gde, date_edit_signals [DATE_CHANGED], 0);
     g_signal_emit (gde, date_edit_signals [TIME_CHANGED], 0);
 
@@ -1020,10 +1017,11 @@ gnc_date_edit_get_date_internal (GNCDateEdit *gde)
         function will have to check this. Alas, I'm too lazy to do this here. */
         gnc_tm_get_today_neutral(&tm);
     }
-
-    tm.tm_mon--;
-
-    tm.tm_year -= 1900;
+    else
+    {
+        tm.tm_mon--;
+        tm.tm_year -= 1900;
+    }
 
     if (gde->flags & GNC_DATE_EDIT_SHOW_TIME)
     {

libgnucash/engine/gnc-date.cpp

@@ -752,7 +752,11 @@ qof_scan_date_internal (const char *buff, int *day, int *month, int *year,
             struct tm thetime;
             /* Parse time string. */
             memset(&thetime, -1, sizeof(struct tm));
-            strptime (buff, normalize_format(GNC_D_FMT).c_str(), &thetime);
+            char *strv = strptime (buff, normalize_format(GNC_D_FMT).c_str(),
+                                   &thetime);
+
+            if (!strv) // Parse failed, continuing gives the wrong result.
+                return FALSE;
 
             if (third_field)
             {