Reference for Megillah 16:17

אי הכי תגלחת וצפרים מ"ט לא דקתני אין בין טהור מתוך הסגר לטהור מתוך החלט אלא תגלחת וצפרים

If that is the case, what is the reason that he is not required to shave and offer birds, as it states: There is no difference between a metzora who has been declared clean after being under observation and one who has been declared clean after having been a definite metzora except shaving and [sacrificing] the birds.

Jastrow