diff --git a/plugins/python-build/test/stubs/stub b/plugins/python-build/test/stubs/stub
index bd5c5d68..5ff72b81 100755
--- a/plugins/python-build/test/stubs/stub
+++ b/plugins/python-build/test/stubs/stub
@@ -11,11 +11,10 @@ _STUB_RUN="${PROGRAM}_STUB_RUN"
 _STUB_INDEX="${PROGRAM}_STUB_INDEX"
 _STUB_RESULT="${PROGRAM}_STUB_RESULT"
 _STUB_END="${PROGRAM}_STUB_END"
-_STUB_DEBUG="${PROGRAM}_STUB_DEBUG"
+_STUB_LOG="${PROGRAM}_STUB_LOG"
 
-if [ -n "${!_STUB_DEBUG}" ]; then
-  echo "$program" "$@" >&${!_STUB_DEBUG}
-fi
+[ -n "${!_STUB_LOG}" ] || eval "${_STUB_LOG}"="${TMPDIR}/${program}-stub-log"
+if test -z "${!_STUB_END}"; then echo "$program" "$@" >>"${!_STUB_LOG}"; fi
 
 [ -e "${!_STUB_PLAN}" ] || exit 1
 [ -n "${!_STUB_RUN}" ] || eval "${_STUB_RUN}"="${TMPDIR}/${program}-stub-run"
@@ -24,7 +23,7 @@ fi
 # Initialize or load the stub run information.
 eval "${_STUB_INDEX}"=1
 eval "${_STUB_RESULT}"=0
-[ ! -e "${!_STUB_RUN}" ] || source "${!_STUB_RUN}"
+if test -e "${!_STUB_RUN}"; then source "${!_STUB_RUN}"; fi
 
 
 # Loop over each line in the plan.
@@ -80,14 +79,39 @@ done < "${!_STUB_PLAN}"
 
 
 if [ -n "${!_STUB_END}" ]; then
-  # Clean up the run file.
-  rm -f "${!_STUB_RUN}"
-
   # If the number of lines in the plan is larger than
   # the requested index, we failed.
   if [ $index -ge "${!_STUB_INDEX}" ]; then
     eval "${_STUB_RESULT}"=1
+    {
+      echo "index: $index; stub index: ${!_STUB_INDEX}"
+      echo "plan:"
+      cat "${!_STUB_PLAN}"
+      echo "run:"
+      cat "${!_STUB_RUN}"
+      echo "log:"
+      cat "${!_STUB_LOG}"
+    } >&2
   fi
+  if [ "${!_STUB_RESULT}" -ne 0 ]; then
+    {
+      echo "index: $index; stub index: ${!_STUB_INDEX}"
+      echo "plan:"
+      cat "${!_STUB_PLAN}" || true
+      echo "run:"
+      cat "${!_STUB_RUN}" || true
+      echo "log:"
+      cat "${!_STUB_LOG}" || true
+    } >&2
+  fi
+
+  # Clean up the run file.
+  rm -f "${!_STUB_RUN}"
+  rm -f "${!_STUB_LOG}"
+
+  # Clean up the run file.
+  rm -f "${!_STUB_RUN}"
+  rm -f "${!_STUB_LOG}"
 
   # Return the result.
   exit "${!_STUB_RESULT}"
diff --git a/plugins/python-build/test/test_helper.bash b/plugins/python-build/test/test_helper.bash
index c7494f64..da52a44f 100644
--- a/plugins/python-build/test/test_helper.bash
+++ b/plugins/python-build/test/test_helper.bash
@@ -25,6 +25,7 @@ stub() {
 
   export "${prefix}_STUB_PLAN"="${TMP}/${program}-stub-plan"
   export "${prefix}_STUB_RUN"="${TMP}/${program}-stub-run"
+  export "${prefix}_STUB_LOG"="${TMP}/${program}-stub-log"
   export "${prefix}_STUB_END"=
 
   mkdir -p "${TMP}/bin"