patch 7.4.1954

Problem:    No test for what 7.4.1948 fixes.
Solution:   Add a test. (Hirohito Higashi, closes #880)

src/testdir/test_increment_dbcs.vim

@@ -0,0 +1,30 @@
+" Tests for using Ctrl-A/Ctrl-X using DBCS.
+if !has('multi_byte')
+  finish
+endif
+set encoding=cp932
+scriptencoding cp932
+
+func SetUp()
+  new
+  set nrformats&
+endfunc
+
+func TearDown()
+  bwipe!
+endfunc
+
+func Test_increment_dbcs_1()
+  set nrformats+=alpha
+  call setline(1, ["<22>R1"])
+  exec "norm! 0\<C-A>"
+  call assert_equal(["<22>R2"], getline(1, '$'))
+  call assert_equal([0, 1, 3, 0], getpos('.'))
+
+  call setline(1, ["<22>`<60>a<EFBFBD>b0xDE<44>e"])
+  exec "norm! 0\<C-X>"
+  call assert_equal(["<22>`<60>a<EFBFBD>b0xDD<44>e"], getline(1, '$'))
+  call assert_equal([0, 1, 10, 0], getpos('.'))
+endfunc
+
+" vim: shiftwidth=2 expandtab