fixed mat.push_back(mat) (ticket #1091)

modules/core/src/matrix.cpp

@@ -579,8 +579,13 @@ void Mat::push_back(const Mat& elems)
     int r = size.p[0], delta = elems.size.p[0];
     if( delta == 0 )
         return;
-    if( this != &elems )
+    if( this == &elems )
     {
+        Mat tmp = elems;
+        push_back(tmp);
+        return;
+    }
+
     size.p[0] = elems.size.p[0];
     bool eq = size == elems.size;
     size.p[0] = r;
@@ -588,7 +593,6 @@ void Mat::push_back(const Mat& elems)
         CV_Error(CV_StsUnmatchedSizes, "");
     if( type() != elems.type() )
         CV_Error(CV_StsUnmatchedFormats, "");
-    }
     
     if( isSubmatrix() || dataend + step.p[0]*delta > datalimit )
         reserve( std::max(r + delta, (r*3+1)/2) );