Those testcases are failing because of
HADOOP-7594 which introduced Jersey dependency, which brings in a bunch of Jackson dependencies as transitive dependencies with version 1.7.1. Among those is jackson-core-asl.
And, hadoop-common declares jackson-mapper-asl which uses version 1.6.9 and has a jackson-core-asl as transitive dependency.
Because hadoop-common does not declare an explicit dependency on jackson-core-asl, and because the transitive occurrences of jackson-core-asl (from jackson-mapper-asl and jersey) are at the same level, the greater version wins.
And it seems that from 1.6.9 to 1.7.1 there are some API changes, we don't know if Jersey is using those APIs.
The safest bet would be to upgrade hadoop-project/pom.xml to use Jackson 1.7.1 and tweak the necessary API calls that changed and we are using.
Maven tip of the day: 'mvn dependency:tree' helps you understand how dependencies are pulled/resolved