Do not silently swallow errors in the write_image deploy step6.4.1

Calling join() does not raise, we need to explicitly check the result.

Change-Id: I81d3d727af220c2b50358edab8139f07874611f0
Story: #2008240
Task: #41083
(cherry picked from commit 420ebc0d73ccfa7248e93881c58a0e45fda0e718)

1 files changed, 11 insertions, 0 deletions

diff --git a/ironic_python_agent/extensions/base.py b/ironic_python_agent/extensions/base.py
index 93adfe93..23e47c46 100644
--- a/ironic_python_agent/extensions/base.py
+++ b/ironic_python_agent/extensions/base.py
@@ -79,6 +79,17 @@ class BaseCommandResult(encoding.SerializableComparable):
         """:returns: result of completed command."""
         return self
 
+    def wait(self):
+        """Join the result and extract its value.
+
+        Raises if the command failed.
+        """
+        self.join()
+        if self.command_error is not None:
+            raise self.command_error
+        else:
+            return self.command_result
+
 
 class SyncCommandResult(BaseCommandResult):
     """A result from a command that executes synchronously."""