perl: make post_make_hook script more robust.

component/perl/buildout.cfg

@@ -25,4 +25,4 @@ configure-command =
     -Dusethreads
 environment =
   PATH=${patch:location}/bin:%(PATH)s
-post-make-hook = ${:_profile_base_location_}/perl-create-libs-symlink.py#539cb3cd0d1090f7f30a8e5a82b37854:post_make_hook
+post-make-hook = ${:_profile_base_location_}/perl-create-libs-symlink.py#28d12de5c9c7985e65233d56817e3bec:post_make_hook

component/perl/perl-create-libs-symlink.py

@@ -20,5 +20,8 @@ def post_make_hook(options, buildout):
   # matches[0] is a prefix of "location"
   # For the symlink, we want the relative path.
   rel_link = os.path.relpath(os.path.dirname(matches[0]), location)
-  os.symlink(rel_link, os.path.join(location, "libs-c"))
+  simlink_location = os.path.join(location, "libs-c")
+  if os.path.islink(simlink_location):
+    os.unlink(simlink_location)
+  os.symlink(rel_link, simlink_location)
   print "Created symlink \"libs-c\" to", rel_link