Maybe, but I doubt it. I'm currently working on another NASA rover project (going to the Moon, not Mars) and we don't use any third party code. Our code is based off of another open source NASA project (Core Flight System), but we don't open-source our exact flight software. Mostly this is simply because we have to go through a lengthy vetting process to ensure we don't inappropriately release anything that falls under ITAR or EAR, and we just don't have the extra time or budget for it.
Typically at NASA it's the more open-ended research projects that have time and support for open sourcing their code. There's less benefit in releasing a specific rover's flight software than there is in releasing the general framework that said software is based on.
