wallet2: fix infinite loop picking outputs in corner case

If we have fewer outputs available on the chain than what we
require, but the output we're spending already has a ring,
it would loop picking outputs randomly, but never find enough.
Also tune logs for better debugging this kind of thing.

src/wallet/wallet2.cpp

@@ -994,7 +994,7 @@ uint64_t gamma_picker::pick()
   const uint64_t n_rct = rct_offsets[index] - first_rct;
   if (n_rct == 0)
     return std::numeric_limits<uint64_t>::max(); // bad pick
-  MDEBUG("Picking 1/" << n_rct << " in block " << index);
+  MTRACE("Picking 1/" << n_rct << " in block " << index);
   return first_rct + crypto::rand_idx(n_rct);
 };
 
@@ -7752,7 +7752,7 @@ void wallet2::get_outs(std::vector<std::vector<tools::wallet2::get_outs_entry>>
         }
       }
 
-      if (num_outs <= requested_outputs_count && !existing_ring_found)
+      if (num_outs <= requested_outputs_count)
       {
         for (uint64_t i = 0; i < num_outs; i++)
           req.outputs.push_back({amount, i});
@@ -7778,6 +7778,8 @@ void wallet2::get_outs(std::vector<std::vector<tools::wallet2::get_outs_entry>>
         // while we still need more mixins
         uint64_t num_usable_outs = num_outs;
         bool allow_blackballed = false;
+        MDEBUG("Starting gamma picking with " << num_outs << ", num_usable_outs " << num_usable_outs
+            << ", requested_outputs_count " << requested_outputs_count);
         while (num_found < requested_outputs_count)
         {
           // if we've gone through every possible output, we've gotten all we can
@@ -7877,6 +7879,7 @@ void wallet2::get_outs(std::vector<std::vector<tools::wallet2::get_outs_entry>>
           picks[type].insert(i);
           req.outputs.push_back({amount, i});
           ++num_found;
+          MDEBUG("picked " << i << ", " << num_found << " now picked");
         }
 
         for (const auto &pick: picks)