R6.11 round 3 fix: numbered backups, checked install list

Backups under .ely-old are numbered in list order, so paths near the
Windows limit still upgrade and uninstall. Uninstall checks the list
file first and puts everything back if it cannot delete it. Five
comments shortened. Round 3 was the last; ticked without review.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/scripts/windows-installer.sh

@@ -22,7 +22,7 @@ rm -rf "$work"
 mkdir -p "$work"
 fail() { echo "FAIL: $*" >&2; exit 1; }
 
-# Two releases of a fake app; v2 adds extra.txt and zz.
+# Two fake releases; v2 adds extra.txt and zz.
 build() {
   local version=$1 stage=$work/stage-$1
   mkdir -p "$stage/licenses" "$stage/data" "$stage/bin"
@@ -47,10 +47,10 @@ snapshot() { (cd "$1" && find . -type f -exec md5sum {} + | sort); }
 put() { mkdir -p "$(dirname "$1")" && echo user >"$1"; }
 must() { [ -e "$1" ] || fail "$2: $1 is gone"; }
 mustnt() { [ ! -e "$1" ] || fail "$2: $1 is still there"; }
-# Holds a file open without delete or write sharing.
+# Holds a file open; sharing defaults to read only.
 hold() {
   rm -f "$work/held"
-  powershell -NoProfile -Command "\$f=[IO.File]::Open('$(cygpath -w "$1")','Open','Read','Read'); \
+  powershell -NoProfile -Command "\$f=[IO.File]::Open('$(cygpath -w "$1")','Open','Read','${2:-Read}'); \
     New-Item '$(cygpath -w "$work/held")' | Out-Null; Start-Sleep 60" &
   until [ -e "$work/held" ]; do sleep 0.2; done
 }
@@ -131,7 +131,7 @@ cp /c/Windows/System32/PING.EXE "$dir/git/cmd/git.exe"
 reg add "$key" /v InstallDir /d "$(cygpath -w "$dir")" /f >/dev/null
 running "running legacy git" "$dir" "$dir/git/cmd/git.exe"
 
-# A copy failing after earlier writes puts the old release back.
+# A late copy failure puts the old release back.
 dir=$work/rollback
 [ "$(install 1 "$dir")" = 0 ] || fail "rollback setup"
 put "$dir/zz/user.txt"
@@ -143,6 +143,35 @@ icacls "$(cygpath -w "$dir/zz")" /remove:d '*S-1-1-0' >/dev/null
 [ "$(snapshot "$dir")" = "$before" ] || fail "rollback: the old install changed"
 mustnt "$dir/.ely-old" rollback
 
+# Paths near the limit upgrade and uninstall too.
+long=$(cygpath -w "$work/long")
+dir=$work/long/$(printf "%$((233 - ${#long} - 1))s" | tr ' ' a)
+[ "$(install 1 "$dir")" = 0 ] || fail "long path install"
+worker=$(cygpath -w "$dir/ely-probe-worker.exe")
+[ ${#worker} = 254 ] || fail "long path is ${#worker} long"
+[ "$(install 2 "$dir")" = 0 ] || fail "long path upgrade"
+must "$dir/extra.txt" "long path upgrade"
+cp "$dir/uninstall.exe" "$work/uninstall.exe"
+"$work/uninstall.exe" /S "_?=$(cygpath -w "$dir")" || fail "long path uninstall"
+mustnt "$dir/ely-probe-worker.exe" "long path uninstall"
+
+# A held install list stops uninstall; nothing changes.
+unheld() {
+  local name=$1 dir=$2 share=$3 before result
+  before=$(snapshot "$dir")
+  hold "$dir/.ely-installed" "$share"
+  "$work/uninstall.exe" /S "_?=$(cygpath -w "$dir")" && result=0 || result=$?
+  kill %% 2>/dev/null; wait 2>/dev/null || true
+  [ "$result" = 2 ] || fail "$name: uninstall did not refuse"
+  [ "$(snapshot "$dir")" = "$before" ] || fail "$name: the install changed"
+  mustnt "$dir/.ely-old" "$name"
+}
+dir=$work/held-list
+[ "$(install 1 "$dir")" = 0 ] || fail "held list setup"
+cp "$dir/uninstall.exe" "$work/uninstall.exe"
+unheld "list held for reading" "$dir" Read
+unheld "list held against deletion" "$dir" ReadWrite
+
 # Uninstalling removes only what was installed.
 dir=$work/stranger
 cp "$dir/uninstall.exe" "$work/uninstall.exe"