_cleanup_dead_links : factored method into a function and put it in llnl.filesystem

lib/spack/llnl/util/filesystem.py

@@ -25,7 +25,7 @@
 __all__ = ['set_install_permissions', 'install', 'install_tree', 'traverse_tree',
            'expand_user', 'working_dir', 'touch', 'touchp', 'mkdirp',
            'force_remove', 'join_path', 'ancestor', 'can_access', 'filter_file',
-           'FileFilter', 'change_sed_delimiter', 'is_exe', 'force_symlink']
+           'FileFilter', 'change_sed_delimiter', 'is_exe', 'force_symlink', 'remove_dead_links']
 
 import os
 import sys
@@ -235,7 +235,7 @@ def touchp(path):
 def force_symlink(src, dest):
     try:
         os.symlink(src, dest)
-    except OSError, e:
+    except OSError as e:
         os.remove(dest)
         os.symlink(src, dest)
 
@@ -339,3 +339,18 @@ def traverse_tree(source_root, dest_root, rel_path='', **kwargs):
 
     if order == 'post':
         yield (source_path, dest_path)
+
+def remove_dead_links(root):
+    """
+    Removes any dead link that is present in root
+
+    Args:
+        root: path where to search for dead links
+
+    """
+    for file in os.listdir(root):
+        path = join_path(root, file)
+        if os.path.islink(path):
+            real_path = os.path.realpath(path)
+            if not os.path.exists(real_path):
+                os.unlink(path)