fix(diff): trigger on_bytes only once after diffget/diffput

Problem: The fix from b50ee4a8dc4306e4be78ac33fb74b21dc6be5538 may
adjust extmark twice, triggering on_bytes callback twice.

Solution: Don't let mark_adjust adjust extmark.

1 files changed, 19 insertions, 0 deletions

diff --git a/test/functional/lua/buffer_updates_spec.lua b/test/functional/lua/buffer_updates_spec.lua
index b1b39501f7..2cd3123dcd 100644
--- a/test/functional/lua/buffer_updates_spec.lua
+++ b/test/functional/lua/buffer_updates_spec.lua
@@ -1171,6 +1171,25 @@ describe('lua: nvim_buf_attach on_bytes', function()
       }
     end)
 
+    it('works with :diffput and :diffget', function()
+      local check_events = setup_eventcheck(verify, {"AAA"})
+      command('diffthis')
+      command('new')
+      command('diffthis')
+      meths.buf_set_lines(0, 0, -1, true, {"AAA", "BBB"})
+      feed('G')
+      command('diffput')
+      check_events {
+        { "test1", "bytes", 1, 3, 1, 0, 4, 0, 0, 0, 1, 0, 4 };
+      }
+      meths.buf_set_lines(0, 0, -1, true, {"AAA", "CCC"})
+      feed('<C-w>pG')
+      command('diffget')
+      check_events {
+        { "test1", "bytes", 1, 4, 1, 0, 4, 1, 0, 4, 1, 0, 4 };
+      }
+    end)
+
     local function test_lockmarks(mode)
       local description = (mode ~= "") and mode or "(baseline)"
       it("test_lockmarks " .. description .. " %delete _", function()