Fixed severe regression in double image mode where the measurement image...

Fixed severe regression in double image mode where the measurement image filename would be copied from the detection image filename (thanks B.Yanny).

src/prefs.c

@@ -22,7 +22,7 @@
 *	You should have received a copy of the GNU General Public License
 *	along with SExtractor. If not, see <http://www.gnu.org/licenses/>.
 *
-*	Last modified:		11/02/2020
+*	Last modified:		19/02/2020
 *
 *%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
@@ -504,6 +504,8 @@ void	useprefs()
 
 /*-------------------------------- Images ----------------------------------*/
   prefs.dimage_flag = (prefs.nimage_name>1);
+  if(!prefs.dimage_flag)
+    strcpy(prefs.image_name[1], prefs.image_name[0]);
 
 /*--------------------------------- ASSOC ----------------------------------*/
   prefs.assoc_flag = FLAG(obj2.assoc) || FLAG(obj2.assoc_number);
@@ -712,13 +714,13 @@ void	useprefs()
 /*-- If detection-only interpolation is needed with 1 Weight image... */
 /*-- ...pretend we're using 2, with only one being interpolated */
     if (prefs.nweight_type==1
-	&& prefs.nwimage_name && prefs.wimage_name[1]==prefs.wimage_name[0]
+	&& prefs.nwimage_name && prefs.nwimage_name < 2
 	&& prefs.interp_type[0]==INTERP_VARONLY )
       {
-      prefs.nweight_type = 2;
-      prefs.weight_type[1] = prefs.weight_type[0];
+      prefs.nwimage_name = prefs.nweight_type = 2;
       prefs.weight_type[0] = WEIGHT_FROMINTERP;
-      prefs.wimage_name[1] = prefs.wimage_name[0];
+      QMEMCPY(prefs.wimage_name[0], prefs.wimage_name[1], char,
+		strlen(prefs.wimage_name[0])+1);
       prefs.interp_type[1] = INTERP_NONE;
       prefs.dweight_flag = 1;
       if (prefs.nweight_thresh<2)