target.frameworks_build_phase can't sucess

project = Xcodeproj::Project.new("MyTest.xcodeproj") # new project
target = project.new_target(:static_library, target_name, :ios, "7.0") # add target
target.frameworks_build_phases.remove_from_project # I don't want to use default configuration
target.frameworks_build_phase # add create new FrameworkBuildPhase
project.save

but FrameworkBuildPhase didn't add to MyTest.xcodeproj. But if MyTest.xcodeproj exists, open the project, do same as above, it can add the new FrameworkBuildPhase to project.

Is it a bug?

Start by reproducing the Ruby snippet that creates a new MyTest.xcodeproj, removes the default frameworks build phase, adds a new one, and saves it; compare this with the same operations on an existing project. Done means the newly created project persists the added FrameworkBuildPhase after project.save.

Written by the indexing model from the issue text.