# HG changeset patch
# User Siddharth Agarwal <sid0@fb.com>
# Date 2017-06-27 21:30:55
# Node ID 0aae80d14fed73b87a4070ce6a38b0f125bc498c
# Parent  98e2c78e309cf750fa6dff6c8965fb24b979022c

bundle2: add some debugging information to the not-a-bundle error

I found this useful while trying to debug wireproto-related issues.

diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -678,6 +678,9 @@ def getunbundler(ui, fp, magicstring=Non
         magicstring = changegroup.readexactly(fp, 4)
     magic, version = magicstring[0:2], magicstring[2:4]
     if magic != 'HG':
+        ui.debug(
+            "error: invalid magic: %r (version %r), should be 'HG'\n"
+            % (magic, version))
         raise error.Abort(_('not a Mercurial bundle'))
     unbundlerclass = formatmap.get(version)
     if unbundlerclass is None: