lib/bb/utils: show subprocess output in stack traces

If better_exec() throws a subprocess.CalledProcessError then show the output to
the user as it likely contains useful information for solving the problem.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/bb/utils.py b/lib/bb/utils.py
index 995089a38..ce52960b4 100644
--- a/lib/bb/utils.py
+++ b/lib/bb/utils.py
@@ -375,6 +375,12 @@ def _print_exception(t, value, tb, realfile, text, context):
             level = level + 1
 
         error.append("Exception: %s" % ''.join(exception))
+
+        # If the exception is from spwaning a task, let's be helpful and display
+        # the output (which hopefully includes stderr).
+        if isinstance(value, subprocess.CalledProcessError):
+            error.append("Subprocess output:")
+            error.append(value.output.decode("utf-8", errors="ignore"))
     finally:
         logger.error("\n".join(error))