After this was posted, Alain COLLONGUES, another significant contributor to this PBP site, offered this additional information:

I have some info about André PETITJEAN which is perhaps interesting for you. His full name was André Antoine PETITJEAN. He was born at 38 avenue de Saint-Mandé in Paris (12ième) on 14 february 1913. So he was the youngest rider of the PBP 1931, the only one born in 1913, all the other ones being born in 1912 or before. Now I know all the dates of birth.

His job was "métreur" that is to say something like "quantity surveyor". In 1931, as it is written in his booklet, he was living in the city of Bry sur Marne, near Paris (15 km). In 1931 he lived with his father who was a joiner and his mother who was housekeeper. He had a brother older than he, whose name was Emile, born in 1906.

I don't know when he died or anything else about him.

[June 7, 2018]