taskdata.py: Improve error message if a task dependency has an incorrect format

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake/lib/bb/taskdata.py

@@ -161,6 +161,8 @@ class TaskData:
                 ids = []
                 for dep in task_deps['depends'][task].split():
                     if dep:
+                        if ":" not in dep:
+                            bb.msg.fatal(bb.msg.domain.TaskData, "Error, dependency %s does not contain ':' character\n. Task 'depends' should be specified in the form 'packagename:task'" % (depend, fn))
                         ids.append(((self.getbuild_id(dep.split(":")[0])), dep.split(":")[1]))
                 self.tasks_idepends[taskid].extend(ids)