I don't have experience bringing or buying a bike overseas, but I do have experience with extended stays overseas.
With the chaos of trying to figure out a new city and a new job, buying a new bike where there may be a language barrier may be a larger burden than you anticipate. Having a bike that already fits and that you are comfortable with will be the easier, more comfortable option.
On the other hand, going to buy a new bike means you may have access to brands that are harder to find here in the US. Also, in the process of finding the new bike you will likely meet other people who like to ride, who may give you good route info and possibly be a new riding partner. To me, this sounds like the more fun option that follows the spirit of moving overseas, but it is dependent on you putting in a little extra effort.
Where in France will you be living?