bitbake: fetch2/local.py: avoid using PREMIRROR

The PREMIRROR isn't useful for "file://", so avoid using it, this is
good for searching speed and can reduce useless lines in log.do_fetch.

(Bitbake rev: e130dca85bac82bd4d88f94a6bf9fe36e8ad4d7c)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/local.py

@@ -126,3 +126,8 @@ class Local(FetchMethod):
     def clean(self, urldata, d):
         return
 
+    def try_premirror(self, urldata, d):
+        """
+        Should premirrors be used?
+        """
+        return False