This is not a question because I already found the answer.

The new Android SDK 17 has a stricter dependency check on jar files.

At the same time, they added a jar that I think wasn't there before. My project encountered a conflict between the new annotations.jar in the SDK and one that I already used. Replacing one by the other would work, if they have the same origin.

My annotations.jar is from jetbrains, via a Guice dependency, so replacing it doesn't work. This is the error I got:

[2012-03-22 10:54:27 - MyApp] Jar mismatch! Fix your dependencies
[2012-03-22 10:54:46 - MyApp] Found 2 versions of annotations.jar in the dependency list,
[2012-03-22 10:54:46 - MyApp] but not all the versions are identical (check is based on SHA-1 only at this time).
[2012-03-22 10:54:46 - MyApp] All versions of the libraries must be the same at this time.
[2012-03-22 10:54:46 - MyApp] Versions found are:
[2012-03-22 10:54:46 - MyApp] Path: /opt/android-sdk-linux_x86/tools/support/annotations.jar
[2012-03-22 10:54:46 - MyApp]   Length: 1463
[2012-03-22 10:54:46 - MyApp]   SHA-1: 6f59fa3a223df6f332bee8b8bffb526f7445018b
[2012-03-22 10:54:46 - MyApp] Path: /home/christine/workspace/MyApp/libs/annotations.jar
[2012-03-22 10:54:46 - MyApp]   Length: 7593
[2012-03-22 10:54:46 - MyApp]   SHA-1: e28fe9e70610beb9ef49226a9e56fed7a86e742a
[2012-03-22 10:54:46 - MyApp] Jar mismatch! Fix your dependencies