clone google 最新的launcher3 Android studio编译报错
Execution failed for task ':generateDebugProto'.

protoc: stdout: . stderr: F:gitoschinaLauncher3srcmainproto: warning: directory does not exist.
F:gitoschinaLauncher3buildextracted-protosmain: warning: directory does not exist.
F:gitoschinaLauncher3buildextracted-include-protosmain: warning: directory does not exist.
F:gitoschinaLauncher3srcdebugproto: warning: directory does not exist.
F:gitoschinaLauncher3buildextracted-protosdebug: warning: directory does not exist.
F:gitoschinaLauncher3buildextracted-include-protosdebug: warning: directory does not exist.
F:gitoschinaLauncher3srcdebugproto: warning: directory does not exist.
F:gitoschinaLauncher3buildextracted-protosdebug: warning: directory does not exist.
F:gitoschinaLauncher3buildextracted-include-protosdebug: warning: directory does not exist.
backup.proto:21:8: Option "javanano_use_deprecated_package" unknown.
at com.google.protobuf.gradle.GenerateProtoTask.compile(GenerateProtoTask.groovy:346)
at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:63)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.doExecute(AnnotationProcessingTaskFactory.java:218)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:211)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:200)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:579)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:562)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
这个要怎么解决呢？
就是http://stackoverflow.com/questions/37934975/android-launcher3-build-fails 这个错误