cros_sdk: display quoted command when it fails

Rather than displaying the list in repr format, use the existing quoted
string property so we can a nicer display.

Before:
 Running ['.../sdk_lib/enter_chroot.sh', '--chroot', '.../chroot', '--', 'false', 'a b c'] failed with exit code 1
After:
 Running {.../sdk_lib/enter_chroot.sh --chroot .../chroot -- false 'a b c'} failed with exit code 1

BUG=None
TEST=`cros_sdk -- false 'a b c'` output can be copied & pasted now

Change-Id: Ibe8b7da3a88426dcad462da8f08f7ab852daccad
Reviewed-on: https://chromium-review.googlesource.com/238051
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cros_sdk.py b/scripts/cros_sdk.py
index 54d27b9..ed068f9 100644
--- a/scripts/cros_sdk.py
+++ b/scripts/cros_sdk.py
@@ -188,8 +188,8 @@
   # interactive; this is however a rare case and the user will immediately
   # see it (nor will they be checking the exit code manually).
   if ret.returncode != 0 and additional_args:
-    raise SystemExit('Running %r failed with exit code %i'
-                     % (cmd, ret.returncode))
+    raise SystemExit('Running {%s} failed with exit code %i'
+                     % (ret.cmdstr, ret.returncode))
 
 
 def _SudoCommand():