[OE-core] [PATCH] bitbake.conf: Default DISTRO to nodistro

[Richard Purdie]

An empty distro value leads to OVERRIDES and FILESOVERRIDES containing
"::" entries which causes odd issues such as files being included when
they shouldn't be. We could put in anonymous python to guard against
empty entries but its messy and setting a default value for DISTRO to
something harmless is much easier.

This patch adds a weak default and ensures the sanity test doesn't
complain about it.

Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
diff --git a/meta/classes/sanity.bbclass b/meta/classes/sanity.bbclass
index b8e5b02..83378b0 100644
--- a/meta/classes/sanity.bbclass
+++ b/meta/classes/sanity.bbclass
@@ -599,7 +599,7 @@ def check_sanity_everybuild(status, d):
     # Check that the DISTRO is valid, if set
     # need to take into account DISTRO renaming DISTRO
     distro = d.getVar('DISTRO', True)
-    if distro:
+    if distro and distro != "nodistro":
         if not ( check_conf_exists("conf/distro/${DISTRO}.conf", d) or check_conf_exists("conf/distro/include/${DISTRO}.inc", d) ):
             status.addresult("DISTRO '%s' not found. Please set a valid DISTRO in your local.conf\n" % d.getVar("DISTRO", True))
 
diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index d7b7a4b..ea313ad 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -656,6 +656,10 @@ AUTO_LIBNAME_PKGS = "${PACKAGES}"
 ### Config file processing
 ###
 
+# An empty distro leads to :: entries in OVERRIDES and FILEOVERRIDES which 
+# is a bad idea. Setting a dummy value is better than a ton of anonymous python.
+DISTRO ??= "nodistro"
+
 # Overrides are processed left to right, so the ones that are named later take precedence.
 # You generally want them to go from least to most specific.
 #