Only abort repository lookups on critical resolution failure Gradle 4.3 introduced an improvement where an error in resolving a module from one repository would prevent Gradle from searching for that same module in subsequent repositories (see #2853).
However, the change to abort searching repositories on _all_ unrecognised errors proved to be too aggressive. With this change, only repository timeout errors will prevent Gradle from searching for a module in a subsequent repository. These timeout errors are considered 'critical' and will blacklist the repository and abort resolution for that module.
In a future release of Gradle, it is likely that we will expand the set of resolution failures that we consider 'critical' to include server errors (HTTP 500) and the like. This commit keeps the set small to miminize impact on the 4.3.1 release.