Commercial software firms are increasingly using and contributing to open source software. Thus, they need to understand and work with open source software development processes. This paper investigates whether the practice of continuous integration of agile software development methods has had an impact on open source software projects. Using fine-granular data from more than 5000 active open source software projects we analyze the size of code contributions over a project’s life-span. Code contribution size has stayed flat. We interpret this to mean that open source software development has not changed its code integration practices. In particular, within the limits of this study, we claim that the practice of continuous integration has not yet significantly influenced the behavior of open source software developers.