When you are told a hadith from the Messenger of Allah ﷺ, assume of the Messenger of Allah ﷺ what is most fitting, most pious, and most rightly guided.Ali came out to us when the caller announced the prayer and said, "Where is the one who was asking about the witr prayer? This is a good time for witr."
حدثنا محمد بن جعفر حدثنا شعبة عن عمرو بن مرة عن أبي البختري عن أبي عبد الرحمن السلمي
إذا حدثتم عن رسول الله ﷺ حديثا فظنوا برسول الله ﷺ أهياه وأتقاه وأهداه وخرج علي علينا حين ثوب المثوب فقال أين السائل عن الوتر هذا حين وتر حسن
Its isnad is sahih, and it is a longer version of the hadith before it. Ibn Majah 1:7 narrated it from Muhammad bin Bashshar, from Muhammad bin Jafar, from Shubah, with this isnad, but he did not mention the other part of it about Ali going out when the call was made. See 974.