base.bbclass: don't backfill features that already exist

It's too easy to cause rebuilds because the DISTRO_FEATURES have changed in
meaningless ways (such as re-ordering or duplicate items).  Help stop this by
checking if the feature to be back-filled is already present.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 3 insertions, 5 deletions

diff --git a/meta/lib/oe/utils.py b/meta/lib/oe/utils.py
index 8d3efe440c..b269f32277 100644
--- a/meta/lib/oe/utils.py
+++ b/meta/lib/oe/utils.py
@@ -96,16 +96,14 @@ def features_backfill(var,d):
     # disturbing distributions that have already set DISTRO_FEATURES.
     # Distributions wanting to elide a value in DISTRO_FEATURES_BACKFILL should
     # add the feature to DISTRO_FEATURES_BACKFILL_CONSIDERED
-
+    features = (d.getVar(var, True) or "").split()
     backfill = (d.getVar(var+"_BACKFILL", True) or "").split()
     considered = (d.getVar(var+"_BACKFILL_CONSIDERED", True) or "").split()
 
     addfeatures = []
     for feature in backfill:
-        if feature not in considered:
+        if feature not in features and feature not in considered:
             addfeatures.append(feature)
 
     if addfeatures:
-        return " %s" % (" ".join(addfeatures))
-    else:
-        return ""
+        d.appendVar(var, " " + " ".join(addfeatures))