libcups: Don't overwrite permanent queue with network during discovery

Currently, if there is a permanent queue of the same name as network
discovered printer, the network one is written in `lpstat -l -e` output.
This is confusing to users and maintainers, because if print job is
sent, it comes to the permanent one instead of listed network/temporary,
which can have a different connection or PPD.

This behavior happens when user creates manually a queue with the same
name as the temporary one, or when the permanent queue is created by
cups-browsed. In both cases user realizes he prints into a different
queue once he enables debugging and see printer-uri in logs.

CHANGES.md

@@ -126,6 +126,8 @@ Changes in CUPS v2.5b1 (YYYY-MM-DD)
 - Fixed error handling when reading a mixed `1setOf` attribute.
 - Fixed how `ippeveprinter` responds to an unsupported request character set.
 - Fixed a recursion issue in `ippReadIO`.
+- Fixed verbose listing of `lpstat -l -e` when permanent queue has the same name
+  as network discovered.
 - Removed hash support for SHA2-512-224 and SHA2-512-256.
 - Removed `mantohtml` script for generating html pages (use
   `https://www.msweet.org/mantohtml/`)

cups/dest.c

@@ -3521,6 +3521,10 @@ cups_get_cb(_cups_getdata_t *data,      // I - Data from cupsGetDests
             unsigned        flags,      // I - Enumeration flags
             cups_dest_t     *dest)      // I - Destination
 {
+  int	diff = 1,			// Result of comparison
+	match;				// Matching index
+
+
   if (flags & CUPS_DEST_FLAGS_REMOVED)
   {
    /*
@@ -3532,10 +3536,14 @@ cups_get_cb(_cups_getdata_t *data,      // I - Data from cupsGetDests
   else
   {
    /*
-    * Add destination to array...
+    * Add destination to array if not present already...
     */
 
-    data->num_dests = cupsCopyDest(dest, data->num_dests, &data->dests);
+    if (data->num_dests)
+      match = cups_find_dest(dest->name, dest->instance, data->num_dests, data->dests, -1, &diff);
+
+    if (diff)
+      data->num_dests = cupsCopyDest(dest, data->num_dests, &data->dests);
   }
 
   return (1);