b. 50
The F1 grace note in GC was added in pencil, which means that Chopin added it in the last phase of preparations of base texts for three editions of Opus 25 (the main goal of these additions was probably the fact of introducing metronome tempos, which are in the form of pencil additions in the manuscripts of 11 etudes). The missing quaver flag in FE is most probably an inaccuracy resulting from haste at the time of performing numerous Chopin corrections. In turn, the notation with the slashed quaver is certainly a result of routine revision of GE (the notation undoubtedly corresponds to the correct performance of this ornament, as only a few Chopin slashed grace notes are to be interpreted as appoggiaturas).
Compare the passage in the sources»
category imprint: Differences between sources; Corrections & alterations
issues: Inaccuracies in FE, Accompaniment changes, Authentic corrections of FE, Authentic corrections in GC
notation: Ornaments