[PATCH] test_common: avoid uninitialized warning on readlink

[Eric Wong]

Of course, waiting for inotify to become active can't rely on
inotify, so we need to do a busy loop here, instead...
---
 lib/PublicInbox/TestCommon.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/PublicInbox/TestCommon.pm b/lib/PublicInbox/TestCommon.pm
index 943dd2fa..ecf7a261 100644
--- a/lib/PublicInbox/TestCommon.pm
+++ b/lib/PublicInbox/TestCommon.pm
@@ -378,7 +378,7 @@ sub wait_for_tail {
                my @ino;
                do {
                        @ino = grep {
-                               readlink($_) =~ /\binotify\b/
+                               (readlink($_) // '') =~ /\binotify\b/
                        } glob("/proc/$tail_pid/fd/*");
                } while (!@ino && time <= $end and tick);
                return if !@ino;