Ideally this should not happen, however due to the large amount of functionality offered in Julia 0.3 as compared to 0.2, many packages became 0.3-compatible only. In that case, of course, you have no choice but to use 0.3 nightlies in order to use those packages.
In the 0.4 development cycle, we're trying to break things down into slightly more granular chunks: We're officially designating these first few crazy months as the 0.4.0-dev period, (reflected in the version numbers of nightlies) wherein everything is fair game for breakage, and some packages will likely break. Once most big changes have had a chance to settle and we start thinking about releasing 0.4.0, we will transition to the 0.4.0-pre phase. This is where a much larger percentage of the userbase can think about starting to use nightly builds, similar to a beta. After that of course, we enter the familiar release candidate phase, followed by a final release. We don't suggest that people who want to use a stable environment use the 0.4.0-dev builds, as I can almost guarantee you a lot of packages will break as soon as we merge a few of the upcoming big changes. It's possible there will be packages that will require 0.4.0-dev features, but most packages that work now should still be compatible with 0.3.0 in the future. That is, after all, what our package manager is meant to do. -E
