oeqa/runCmd: print stderr when that is a separate stream

runCmd by default merges stderr into stdout, and only
needs to print stdout when errors occur. When stderr
is requested as a separate stream, and an error occurs,
stderr is discarded, obscuring useful error messages.
This changes the output to include both streams.

(From OE-Core rev: 72c747b37ccdd486ddae06e3d0a99fb2b93643ba)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/commands.py

@@ -203,6 +203,8 @@ def runCmd(command, ignore_status=False, timeout=None, assert_error=True, sync=T
 
     if result.status and not ignore_status:
         exc_output = result.output
+        if result.error:
+            exc_output = exc_output + result.error
         if limit_exc_output > 0:
             split = result.output.splitlines()
             if len(split) > limit_exc_output: