Re #1750 comments on situation when symmetry operation should or shou…

…ld not be used.

horace_core/sqw/@sqw/private/cut_accumulate_data_.m

@@ -195,6 +195,10 @@
     t_proj_start = tic;
 end
 
+% multiple projections here can appear only from multiple symmetries, so 
+% if only one projection is there, no symmetries will be used
+apply_symmetries = num_proj > 1;
+
 for iter = 1:num_chunks
     % Get pixels that will likely contribute to the cut
     chunk = block_chunks{iter};
@@ -215,14 +219,14 @@
             iter, num_chunks, candidate_pix.num_pixels);
     end
 
-    apply_symmetries = num_proj > 1;
     for i = 1:num_proj
-
         % Pix not sorted here
         [npix, s, e, pix_ok, unique_runid_l, pix_indx, selected] = ...
             targ_proj(i).bin_pixels(targ_axes(i), candidate_pix, npix, s, e);
 
-        if apply_symmetries
+        % if there are symmetries, we need to transform pixels and tag used
+        % pixels to avoid multiple usage of the same pixels.
+        if apply_symmetries 
             candidate_pix = sym{i}.transform_pix(candidate_pix, {}, selected);
             candidate_pix = candidate_pix.tag(selected);
         end