[PATCH] fetch2: Enhance error message for BB_NO_NETWORK

[Richard Purdie <richard.purdie@linuxfoundation.org>]

BB_NO_NETWORK can be set by bitbake internally by the use of
BB_FETCH_PREMIRRORONLY so update the error message to give users a
hint about this.

[YOCTO #3222]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/bitbake/lib/bb/fetch2/__init__.py b/bitbake/lib/bb/fetch2/__init__.py
index 1365335..adbbf30 100644
--- a/bitbake/lib/bb/fetch2/__init__.py
+++ b/bitbake/lib/bb/fetch2/__init__.py
@@ -121,7 +121,7 @@ class ParameterError(BBFetchException):
 class NetworkAccess(BBFetchException):
     """Exception raised when network access is disabled but it is required."""
     def __init__(self, url, cmd):
-         msg = "Network access disabled through BB_NO_NETWORK but access requested with command %s (for url %s)" % (cmd, url)
+         msg = "Network access disabled through BB_NO_NETWORK (or set indirectly due to use of BB_FETCH_PREMIRRORONLY) but access requested with command %s (for url %s)" % (cmd, url)
          self.url = url
          self.cmd = cmd
          BBFetchException.__init__(self, msg)