Merge branch 'tg/range-diff-corner-case-fix'

Recently added "range-diff" had a corner-case bug to cause it
segfault, which has been corrected.

* tg/range-diff-corner-case-fix:
  linear-assignment: fix potential out of bounds memory access

linear-assignment.c

@@ -19,6 +19,12 @@ void compute_assignment(int column_count, int row_count, int *cost,
 	int *free_row, free_count = 0, saved_free_count, *pred, *col;
 	int i, j, phase;
 
+	if (column_count < 2) {
+		memset(column2row, 0, sizeof(int) * column_count);
+		memset(row2column, 0, sizeof(int) * row_count);
+		return;
+	}
+
 	memset(column2row, -1, sizeof(int) * column_count);
 	memset(row2column, -1, sizeof(int) * row_count);
 	ALLOC_ARRAY(v, column_count);

t/t3206-range-diff.sh

@@ -122,6 +122,11 @@ test_expect_success 'changed commit' '
 	test_cmp expected actual
 '
 
+test_expect_success 'no commits on one side' '
+	git commit --amend -m "new message" &&
+	git range-diff master HEAD@{1} HEAD
+'
+
 test_expect_success 'changed message' '
 	git range-diff --no-color topic...changed-message >actual &&
 	sed s/Z/\ /g >expected <<-EOF &&