fix oversight

Author: dkarrasch

stdlib/LinearAlgebra/src/triangular.jl

@@ -1227,12 +1227,12 @@ function generic_trimatdiv!(C::AbstractVecOrMat, uploc, isunitc, tfun::Function,
             end
         else # isunitc == 'U'
             if tfun === identity
-                C1 = C[1,k] = oA \ B[1,k]
-                # fill C-column
-                for i in 2:m
-                    C[i,k] = oA \ B[i,k] - _ustrip(A[i,1]) * C1
-                end
                 for k in 1:n
+                    C1 = C[1,k] = oA \ B[1,k]
+                    # fill C-column
+                    for i in 2:m
+                        C[i,k] = oA \ B[i,k] - _ustrip(A[i,1]) * C1
+                    end
                     for j in 2:m
                         Cj = C[j,k]
                         for i in j+1:m