The errors are very useful when debugging qtest failures, especially when
QTEST_LOG=1 is set.  Let's allow override MigrateStart.hide_stderr when
QTEST_LOG=1 is specified, because that means the user wants to be verbose.

Not very nice to introduce the first QTEST_LOG env access in migration-test.c,
however it should be handy.  Without this patch, I was hacking error_report()
when debugging such errors.  Let's make things easier.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tests/qtest/migration-test.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index 00a233cd8c..ff9ed70029 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -461,6 +461,10 @@ static void migrate_postcopy_start(QTestState *from, QTestState *to)
 }
 
 typedef struct {
+    /*
+     * QTEST_LOG=1 may override this.  When QTEST_LOG=1, we always dump errors
+     * unconditionally, because it means the user would like to be verbose.
+     */
     bool hide_stderr;
     bool use_shmem;
     /* only launch the target process */
@@ -554,7 +558,7 @@ static int test_migrate_start(QTestState **from, QTestState **to,
 
     g_free(bootpath);
 
-    if (args->hide_stderr) {
+    if (!getenv("QTEST_LOG") && args->hide_stderr) {
         ignore_stderr = "2>/dev/null";
     } else {
         ignore_stderr = "";
-- 
2.26.2