Mishna Berura (סימן עה, ס' ג, ס'ק טו):
וכתב הפמ"ג דבמדינות שיוצאין הנשים בפיאה נכרית מגולה יש להם לסמוך על השו"ע ומשמע מיניה שם דאפילו שער של עצמה שנחתך ואח"כ חברה לראשה ג"כ יש להקל ובספר מגן גבורים החמיר בזה עי"ש.
The Peri Megadim writes that in those countries were women wear wigs, they can rely on the Shulchan Aruch. One can infer from this, that even one's own hair that was cut off, and then later reattached, one can be lenient (and this counts as a hair-covering). The Magen Giborim was strict in this matter.
The relevant part to this question translates as: "… The Peri Megadim writes… even one's own hair that has been cut and afterwards attached to their head [as a wig], we are lenient. But the 'Magen Giborim' is stringent [in this matter]".(free translation; text copied from here)
