fix(update): fetch --tags --force so moved upstream tags don't fail the fetch

CHANGELOG.md

@@ -39,6 +39,17 @@ All notable changes to the Vim Plugin Manager will be documented in this file.
   startup check re-fetches (TTL skipped). It was previously accepted
   but ignored.
 
+### Fixed
+- Update no longer reports "Fetch failed" when an upstream tag moved: the
+  update fetch is `git fetch --tags --force origin`, so a tag-clobber
+  rejection (local tag object differing from the remote one) refreshes
+  the tag mirror instead of failing the whole fetch - branch refs were
+  already updating successfully in that case. Local tags in a plugin
+  submodule are mirrors of upstream, never local creations, so the
+  forced refresh matches the pull trust level. Diagnosed on a real
+  setup: 12 stale v1.x/v2.1.x tag mirrors were poisoning every update
+  of the affected module.
+
 ### Removed
 - Dead code: never-read async job state fields (`id`, `started`,
   `queued`), the unused `g:plugin_manager_periodic_timer` write, four

autoload/plugin_manager/cmd/update.vim

@@ -88,7 +88,7 @@ function! s:update_specific_plugin_async(ctx) abort
 
   " Step 1: Fetch first, stash only if a pull turns out to be needed
   call plugin_manager#ui#update_operation(l:op_id, 'Fetching updates')
-  call plugin_manager#async#git('git -C ' . shellescape(a:ctx.module_path) . ' fetch --tags origin', {
+  call plugin_manager#async#git('git -C ' . shellescape(a:ctx.module_path) . ' fetch --tags --force origin', {
         \ 'callback': function('s:on_fetch_complete', [a:ctx])
         \ })
 endfunction
@@ -385,7 +385,7 @@ function! s:update_all_plugins_async(ctx) abort
   for l:module in a:ctx.valid_modules
     let l:module_path = get(l:module, 'abs_path', l:module.path)
     call plugin_manager#async#git(
-          \ 'git -C ' . shellescape(l:module_path) . ' fetch --tags origin', {
+          \ 'git -C ' . shellescape(l:module_path) . ' fetch --tags --force origin', {
           \ 'callback': function('s:on_module_fetched', [a:ctx, l:module])
           \ })
   endfor

tests/update.vader

@@ -326,3 +326,28 @@ Execute (custom-branch module is skipped with the exact skip message):
   call system('git -C ' . shellescape(g:_pm_upd_plug) . ' checkout -q main')
   call system('git -C ' . shellescape(g:_pm_upd_plug) . ' branch -D dev')
   unlet g:_pm_upd_sb
+
+Execute (a moved upstream tag does not fail the fetch):
+  " Upstream tags can move (re-annotated).  The module's local tag copy is
+  " a mirror, never a local creation: git fetch --tags --force must refresh
+  " it instead of failing the whole fetch (branch refs update regardless;
+  " a plain tag rejection must not mark the module as failed).
+  call system('git -C ' . shellescape(g:_pm_upd_tmp_src) . ' tag -a v9.9.9 -m rel')
+  call system('git -C ' . shellescape(g:_pm_upd_tmp_src) . ' push -q origin v9.9.9')
+  " Local tag with a DIFFERENT tag-object SHA than the remote one.
+  call system('git -C ' . shellescape(g:_pm_upd_plug) . ' tag -a v9.9.9 -m local')
+  call plugin_manager#cmd#dispatch('update')
+  let g:_pm_upd_sb = join(getbufline(bufnr('PluginManager'), 1, '$'), "\n")
+  Assert g:_pm_upd_sb !~# 'Fetch failed',
+        \ 'a tag clobber rejection must not fail the fetch, got: ' . g:_pm_upd_sb
+  " The local tag mirror is refreshed to the remote tag object.
+  let g:_pm_upd_local_tag = substitute(
+        \ system('git -C ' . shellescape(g:_pm_upd_plug) . ' show-ref --tags v9.9.9'),
+        \ '\n', '', 'g')
+  let g:_pm_upd_remote_tag = substitute(
+        \ system('git -C ' . shellescape(g:_pm_upd_tmp_src) . ' show-ref --tags v9.9.9'),
+        \ '\n', '', 'g')
+  Assert g:_pm_upd_local_tag ==# g:_pm_upd_remote_tag,
+        \ 'tag must be refreshed to the remote object, got: '
+        \ . g:_pm_upd_local_tag . ' vs ' . g:_pm_upd_remote_tag
+  unlet g:_pm_upd_sb g:_pm_upd_local_tag g:_pm_upd_remote_tag