[PATCH] pygrub: always append --args

[Olaf Hering <olaf@aepfle.de>]

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1346945306 -7200
# Node ID 8a2eef481d3ab3ca5692dd0083c95cf314fe1da3
# Parent  19d367bf07b7687b831c212a57a70e73ea14d3b7
pygrub: always append --args

If a bootloader entry in menu.lst has no additional kernel command line
options listed and the domU.cfg has 'bootargs="--args=something"' the
additional arguments from the config file are not passed to the kernel.
The reason for that incorrect behaviour is that run_grub appends arg
only if the parsed config file has arguments listed.

Fix this by appending args from image section and the config file separatly.
To avoid adding to a NoneType initialize grubcfg['args'] to an empty string.
This does not change behaviour but simplifies the code which appends the
string.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r 19d367bf07b7 -r 8a2eef481d3a tools/pygrub/src/pygrub
--- a/tools/pygrub/src/pygrub
+++ b/tools/pygrub/src/pygrub
@@ -615,13 +615,15 @@ def run_grub(file, entry, fs, arg):
     except IndexError:
         img = g.cf.images[0]
 
-    grubcfg = { "kernel": None, "ramdisk": None, "args": None }
+    grubcfg = { "kernel": None, "ramdisk": None, "args": "" }
 
     grubcfg["kernel"] = img.kernel[1]
     if img.initrd:
         grubcfg["ramdisk"] = img.initrd[1]
     if img.args:
-        grubcfg["args"] = img.args + " " + arg
+        grubcfg["args"] += img.args
+    if arg:
+        grubcfg["args"] += " " + args
 
     return grubcfg