fix: changedelete symbol with linematch enabled

Since linematch will report a changed line following deleted lines as
multiple hunks on a single line, it will only show the `changed` sign
and will drop the `deleted` sign.  To fix this check for overlapping
hunks and mark the change hunk as changedelete.

lua/gitsigns/hunks.lua

@@ -164,11 +164,12 @@ end
 
 --- Calculate signs needed to be applied from a hunk for a specified line range.
 --- @param hunk Gitsigns.Hunk.Hunk
+--- @param next Gitsigns.Hunk.Hunk?
 --- @param min_lnum integer
 --- @param max_lnum integer
 --- @param untracked boolean
 --- @return Gitsigns.Sign[]
-function M.calc_signs(hunk, min_lnum, max_lnum, untracked)
+function M.calc_signs(hunk, next, min_lnum, max_lnum, untracked)
   assert(
     not untracked or hunk.type == 'add',
     string.format('Invalid hunk with untracked=%s hunk="%s"', untracked, hunk.head)
@@ -191,11 +192,21 @@ function M.calc_signs(hunk, min_lnum, max_lnum, untracked)
 
   local cend = change_end(hunk)
 
-  for lnum = max(start, min_lnum), min(cend, max_lnum) do
-    local changedelete = hunk.type == 'change' and removed > added and lnum == cend
+  -- if this is a change hunk, mark changedelete if lines were removed or if the
+  -- next hunk removes on this hunks last line
+  local changedelete = false
+  if hunk.type == 'change' then
+    changedelete = removed > added
+    if next ~= nil and next.type == 'delete' then
+      changedelete = changedelete or hunk.added.start + hunk.added.count - 1 == next.added.start
+    end
+  end
 
+  for lnum = max(start, min_lnum), min(cend, max_lnum) do
     signs[#signs + 1] = {
-      type = changedelete and 'changedelete' or untracked and 'untracked' or hunk.type,
+      type = (changedelete and lnum == cend) and 'changedelete'
+        or untracked and 'untracked'
+        or hunk.type,
       count = lnum == start and (hunk.type == 'add' and added or removed) or nil,
       lnum = lnum,
     }

lua/gitsigns/manager.lua

@@ -41,16 +41,22 @@ local function apply_win_signs0(bufnr, signs, hunks, top, bot, clear, untracked)
   end
 
   for i, hunk in ipairs(hunks or {}) do
+    --- @type Gitsigns.Hunk.Hunk?
+    local next = hunks[i + 1]
+
     -- To stop the sign column width changing too much, if there are signs to be
     -- added but none of them are visible in the window, then make sure to add at
     -- least one sign. Only do this on the first call after an update when we all
     -- the signs have been cleared.
     if clear and i == 1 then
-      signs:add(bufnr, gs_hunks.calc_signs(hunk, hunk.added.start, hunk.added.start, untracked))
+      signs:add(
+        bufnr,
+        gs_hunks.calc_signs(hunk, next, hunk.added.start, hunk.added.start, untracked)
+      )
     end
 
     if top <= hunk.vend and bot >= hunk.added.start then
-      signs:add(bufnr, gs_hunks.calc_signs(hunk, top, bot, untracked))
+      signs:add(bufnr, gs_hunks.calc_signs(hunk, next, top, bot, untracked))
     end
     if hunk.added.start > bot then
       break