Fix rez-pkg-cache to preserve symlinks instead of following them

By default, shutil.copytree follows symlinks which can cause failures
when symlink targets are inaccessible. This change adds symlinks=True
parameter to preserve symlinks instead of following them, matching the
default behavior of rez-cp.

Fixes #2047

Signed-off-by: pmady <pavan4devops@gmail.com>

Author: pmady

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 <!-- start-here-sphinx-start-after -->
 
+## Unreleased
+
+### Fixes
+- Fix `rez-pkg-cache` to preserve symlinks instead of following them [\#2047](https://github.com/AcademySoftwareFoundation/rez/issues/2047)
+
 ## v3.3.0 (2025-10-17)
 [Source](https://github.com/AcademySoftwareFoundation/rez/tree/3.3.0) | [Diff](https://github.com/AcademySoftwareFoundation/rez/compare/v3.2.1...3.3.0)
 

src/rez/package_cache.py

@@ -405,7 +405,7 @@ def _while_copying():
         th.start()
 
         try:
-            shutil.copytree(variant_root, rootpath)
+            shutil.copytree(variant_root, rootpath, symlinks=True)
         finally:
             still_copying = False