# HG changeset patch
# User Alain Leufroy
# Date 1614465538 -3600
#      Sat Feb 27 23:38:58 2021 +0100
# Node ID ce9bbc83cd90ac66f26c76bd784247c8e47b1406
# Parent  70efdbf65a93afdf96f5fc4272e623552befa770
edit: ignore fully empty file

diff --git a/overlayctl b/overlayctl
--- a/overlayctl
+++ b/overlayctl
@@ -408,7 +408,7 @@
     if not appended and not prepanded and not removed:
         with NamedTemporaryFile() as fobj:
             fobj.write(b'# -*- encoding: utf-8 -*-\n')
-            fobj.write(b'# Note: Leave unchanged or empty to ignore changes\n')
+            fobj.write(b'# Note: Leave unchanged or fully empty to ignore changes\n')
             fobj.write(b'\n'.join(lower.encode('utf-8') for lower in info['lowers']))
             fobj.flush()
             Popen(os.environ.get('EDITOR', 'vim') + ' ' + fobj.name, shell=True).wait()
@@ -418,6 +418,9 @@
                 for line in fobj.read().decode('utf-8').splitlines()
                 if not line.strip().startswith('#') and line.strip()
             ]
+            fobj.seek(0)
+            if not fobj.read(1):
+                return  # Ignore empty file for convenience
     else:
         prepanded = prepanded or []
         added = appended or []