Handle keyboard interrupt during build

lib/webports/source_package.py

Index: lib/webports/source_package.py
diff --git a/lib/webports/source_package.py b/lib/webports/source_package.py
index efc073cd4294302fdb14e860c5da53420f61c663..08f0809512580b8a8d2a1867df57ba5bce485199 100644
--- a/lib/webports/source_package.py
+++ b/lib/webports/source_package.py
@@ -365,6 +365,10 @@ class SourcePackage(package.Package):
             self.CreatePkgFile()
           finally:
             util.log_level = old_log_level
+      except KeyboardInterrupt:
+        # Treat KeyboardInterrupt as special, and not an actual failure.  This
+        # avoid log spew to stdout when they user interupts a quit build.
+        raise
       except:
         if log_filename:
           with open(log_filename) as log_file: