patch 8.0.1039: cannot change a line in not current buffer

Problem:    Cannot change a line in a buffer other than the current one.
Solution:   Add setbufline(). (Yasuhiro Matsumoto, Ozaki Kiichi, closes #1953)
diff --git a/src/testdir/test_alot.vim b/src/testdir/test_alot.vim
index e83256a..189cd82 100644
--- a/src/testdir/test_alot.vim
+++ b/src/testdir/test_alot.vim
@@ -3,6 +3,7 @@
 
 set belloff=all
 source test_assign.vim
+source test_bufline.vim
 source test_cd.vim
 source test_changedtick.vim
 source test_cursor_func.vim
diff --git a/src/testdir/test_bufline.vim b/src/testdir/test_bufline.vim
new file mode 100644
index 0000000..7df36aa
--- /dev/null
+++ b/src/testdir/test_bufline.vim
@@ -0,0 +1,26 @@
+" Tests for setbufline() and getbufline()
+
+func Test_setbufline_getbufline()
+  new
+  let b = bufnr('%')
+  hide
+  call assert_equal(0, setbufline(b, 1, ['foo', 'bar']))
+  call assert_equal(['foo'], getbufline(b, 1))
+  call assert_equal(['bar'], getbufline(b, 2))
+  call assert_equal(['foo', 'bar'], getbufline(b, 1, 2))
+  exe "bd!" b
+  call assert_equal([], getbufline(b, 1, 2))
+
+  split Xtest
+  call setline(1, ['a', 'b', 'c'])
+  let b = bufnr('%')
+  wincmd w
+  call assert_equal(1, setbufline(b, 5, ['x']))
+  call assert_equal(1, setbufline(1234, 1, ['x']))
+  call assert_equal(0, setbufline(b, 4, ['d', 'e']))
+  call assert_equal(['c'], getbufline(b, 3))
+  call assert_equal(['d'], getbufline(b, 4))
+  call assert_equal(['e'], getbufline(b, 5))
+  call assert_equal([], getbufline(b, 6))
+  exe "bwipe! " . b
+endfunc