Description of problem:
Package swift-lang fails to build from source in Fedora rawhide with following error:

Traceback (most recent call last):
  File "/builddir/build/BUILD/swift-source/swift/utils/gyb", line 3, in <module>
    gyb.main()
  File "/builddir/build/BUILD/swift-source/swift/utils/gyb.py", line 1260, in main
    args.target.write(execute_template(ast, args.line_directive, **bindings))
  File "/builddir/build/BUILD/swift-source/swift/utils/gyb.py", line 1131, in execute_template
    ast.execute(execution_context)
  File "/builddir/build/BUILD/swift-source/swift/utils/gyb.py", line 635, in execute
    x.execute(context)
  File "/builddir/build/BUILD/swift-source/swift/utils/gyb.py", line 721, in execute
    result = eval(self.code, context.local_bindings)
  File "/builddir/build/BUILD/swift-source/swift/stdlib/public/core/IntegerTypes.swift.gyb", line 20, in <module>
    from string import maketrans, capitalize
ImportError: cannot import name 'maketrans' from 'string' (/usr/lib64/python3.7/string.py)

Version-Release number of selected component (if applicable):
5.0.1-0.56.20190418git604054e.fc31

Dependency changes from the last successful build can be found 
https://apps.fedoraproject.org/koschei/build/6686933

The main changes is
  python-unversioned-command 2.7.16-2.fc31 -> 3.7.4-3.fc31


Additional info:
This package is tracked by Koschei. See:
http://apps.fedoraproject.org/koschei/package/swift-lang