(GH-141) Fix renaming a dir with sub-directories

[da-ar]

This is an update to #239 to address the open comments, and rebased off master

[CLAassistant]

All committers have signed the CLA.

[jxsl13]

what happens if you have got
two sub directories called

/subdir1/whatever/
/subdir10/whatever1/

and you try to rename subdir1?

[spf13]

The fix is in the right direction but has two bugs that need addressing before this can merge:

1. Data race in the range loop. You're doing a lock upgrade (RUnlock → Lock → mutate → Unlock → RLock) inside a range over the same map you're mutating. This is a data race: the range iterator's internal state is invalidated by the concurrent mutation. Collect the keys to rename first, then mutate in a second pass:

   // collect under read lock
   m.mu.RLock()
   var toRename []string
   for p := range m.getData() {
       if strings.HasPrefix(p, oldname+"/") || p == oldname {
           toRename = append(toRename, p)
       }
   }
   m.mu.RUnlock()
   // mutate under write lock
   m.mu.Lock()
   for _, p := range toRename {
       newP := newname + p[len(oldname):]
       m.getData()[newP] = m.getData()[p]
       delete(m.getData(), p)
   }
   m.mu.Unlock()

2. Prefix collision. strings.HasPrefix(p, oldname) matches /subdir10 when renaming /subdir1. The prefix check must be strings.HasPrefix(p, oldname+"/") (or normalizePath(oldname)+FilePathSeparator).

Fix both and this is mergeable.

[spf13]

Thanks for this — the bug you identified was real. However, this fix is now already in the codebase via renameDescendants(), which was added in a subsequent commit and handles this case correctly (and avoids the path-prefix collision that would affect your HasPrefix check, e.g. renaming /src incorrectly matching /src-other). Closing as already fixed.