Retire support for storage v6

lib/filesystem.py

@@ -1175,7 +1175,7 @@ def init(self):
       if (v_found == STORAGE_VERSION):
          ch.VERBOSE("found storage dir v%d: %s" % (STORAGE_VERSION, self.root))
          self.lock()
-      elif (v_found in {None, 6}):  # initialize/upgrade
+      elif (v_found is None):  # initialize/upgrade
          ch.INFO("%s storage directory: v%d %s"
                  % (op, STORAGE_VERSION, self.root))
          self.root.mkdir()
@@ -1188,16 +1188,6 @@ def init(self):
          self.build_large.mkdir()
          self.unpack_base.mkdir()
          self.upload_cache.mkdir()
-         if (v_found is not None):  # upgrade
-            if (v_found == 6):
-               # Charliecloud 0.32 had a bug where symlinks to fat manifests
-               # that were really skinny were erroneously absolute, making the
-               # storage directory immovable (PR #1657). Remove all symlinks
-               # in dlcache; they’ll be re-created later.
-               for entry in self.download_cache.iterdir():
-                  if (entry.is_symlink()):
-                     ch.DEBUG("deleting bad v6 symlink: %s" % entry)
-                     entry.unlink()
          self.version_file.file_write("%d\n" % STORAGE_VERSION)
       else:                         # can’t upgrade
          ch.FATAL("incompatible storage directory v%d: %s"
@@ -1294,10 +1284,8 @@ def validate_strict(self):
                      % (msg_prefix, img), ch.BUG_REPORT_PLZ)
 
    def version_read(self):
-      # While support for storage v1 was dropped some time ago, let’s at least
-      # retain the ability to recognize it.
       if (not os.path.isfile(self.version_file)):
-         return 1
+         ch.FATAL('Expected file "%s" not found' % self.version_file)
       text = self.version_file.file_read_all()
       try:
          return int(text)