+file to speed up future invocations. It always safe to remove
+manifest.js.gz, it is merely an optimization and will be
+restored on the next invocation.
+
+To prevent fetches on any v2 epoch, use L<chmod(1)> to remove
+write permissions to the top-level of the epoch. For example,
+to disable fetches on epoch 4:
+
+ chmod a-w $INBOX_DIR/git/4.git
+
+If you wish to re-enable fetches to the epoch:
+
+ chmod u+w $INBOX_DIR/git/4.git