made no-prefix target selection work nicer
diff --git a/aos/build/build.py b/aos/build/build.py
index 6a728ed..ac316ce 100755
--- a/aos/build/build.py
+++ b/aos/build/build.py
@@ -191,7 +191,10 @@
elif part[0] == '=':
r = self.select_platforms_string(part[1:])
else:
- r = r - (self.platforms - self.select_platforms_string(part))
+ selected = self.select_platforms_string(part)
+ r = r - (self.platforms - selected)
+ if not r:
+ r = selected
return r
def select_platforms(self, architecture=None, compiler=None, debug=None):