oeqa: add proper handling for command errors where needed

For use outside of tests themselves, we want a better error than
AssertionError, so create one and allow us to request it when calling
runCmd(). This enables us to avoid tracebacks during master image
operations if the power control command fails.

(From OE-Core rev: 89868383685091b0d3723fb8f29590f3f6610078)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/controllers/masterimage.py

@@ -20,6 +20,7 @@ import subprocess
 import oeqa.targetcontrol
 import oeqa.utils.sshcontrol as sshcontrol
 import oeqa.utils.commands as commands
+from oeqa.utils import CommandError
 
 from abc import ABCMeta, abstractmethod
 
@@ -94,7 +95,10 @@ class MasterImageHardwareTarget(oeqa.targetcontrol.BaseTarget):
     def power_ctl(self, msg):
         if self.powercontrol_cmd:
             cmd = "%s %s" % (self.powercontrol_cmd, msg)
-            commands.runCmd(cmd, preexec_fn=os.setsid, env=self.origenv)
+            try:
+                commands.runCmd(cmd, assert_error=False, preexec_fn=os.setsid, env=self.origenv)
+            except CommandError as e:
+                bb.fatal(str(e))
 
     def power_cycle(self, conn):
         if self.powercontrol_cmd: