The GPars Gradle build is causing faulty SHA1 signatures to be written in the Codehaus repository during an uploadArchives task. This is something specific to the GPars build, since if I do a Gant uploadArchives on the same machine to the same Codehaus snapshots repository the SHA1 signatures written are correct. Certainly I think we can rule out my machine as the culprit and also Codehaus – at least per se.
(Russel Winder)

We also had this problem with some of the NoSQL jars we published and it is a serious problem. A previous workaround I used was to to publish first with the webdav-jackrabbit wagon (1.0-beta-7) Unfortunately this resulted in bad SHA1 signatures so afterwards I published again using the plain HTTP wagon "org.apache.maven.wagon:wagon-http:1.0-beta-6"
Note you can't publish the first time with the plain HTTP wagon, because it fails to create the proper directory structure
This worked once, but recently I tried the same process and failed miserably. I had to generate valid SHA1 files for each jar/pom and manually connect to the Codehaus repo and overwrite them by hand to fix the problem
(Graeme Rocher)

Luke Daley has meanwhile suggested using wagon-http-lightweight:1.0-beta-6, which seems to work for me, although with the same directory creation limitation.