* Flag `--no-build-hook' to disable distributed builds.

* queryDeriver in daemon mode: don't barf if the other side returns an
  empty string (which means there is no deriver).

src/libstore/globals.hh

@@ -72,6 +72,10 @@ extern unsigned int maxSilentTime;
    from a CD. */
 extern Paths substituters;
 
+/* Whether to use build hooks (for distributed builds).  Sometimes
+   users want to disable this from the command-line. */
+extern bool useBuildHook;
+
 
 Strings querySetting(const string & name, const Strings & def);