I noticed this this morning when a Jenkins build failed on me:
FAILURE: Build failed with an exception.
* What went wrong:
Could not resolve all dependencies for configuration ':forgeGradleUserDevPackage'.
> Could not download forge-userdev.jar (net.minecraftforge:forge:1.12.2-220.127.116.1172)
> Could not close resource 'http://files.minecraftforge.net/maven/net/minecraftforge/forge/1.12.2-18.104.22.16872/forge-1.12.2-22.214.171.12472-userdev.jar'.
> Premature end of Content-Length delimited message body (expected: 5199526; received: 86587
Trying with wget also reports an error, but wget auto-retries and manages to get the JAR ok. Unfortunately, gradle (as run from Jenkins above, and also from the local command-line) gives up and fails the build immediately. This seems to be pretty reproducable and happens both on my local machine and a remote Jenkins build server.
Something up with files.minecraftforge.net?