prepare fails

[sciurius]

swift-driver version: 1.62.15 Apple Swift version 5.7.2 (swiftlang-5.7.2.135.5 clang-1400.0.29.51)
Target: x86_64-apple-macosx12.0

% ./prepare    
Traceback (most recent call last):
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb", line 3, in <module>
   gyb.main()
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 1251, in main
   result_text = execute_template(ast, args.line_directive, **bindings)
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 1124, in execute_template
   ast.execute(execution_context)
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 626, in execute
   x.execute(context)
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 712, in execute
   result = eval(self.code, context.local_bindings)
 File "/Users/chordpro/tmp/swiftperl/Sources/Perl/Subroutine.swift.gyb", line 234, in <module>
   %   for p in paramsRange(tail):
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 626, in execute
   x.execute(context)
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 712, in execute
   result = eval(self.code, context.local_bindings)
 File "/Users/chordpro/tmp/swiftperl/Sources/Perl/Subroutine.swift.gyb", line 234, in <module>
   %   for p in paramsRange(tail):
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 626, in execute
   x.execute(context)
 File "/Users/chordpro/tmp/swiftperl/.build/gyb/gyb.py", line 712, in execute
   result = eval(self.code, context.local_bindings)
 File "/Users/chordpro/tmp/swiftperl/Sources/Perl/Subroutine.swift.gyb", line 233, in <module>
   % for tail in ("fixed", "array", "hash"):
 File "/Users/chordpro/tmp/swiftperl/Sources/Perl/Subroutine.swift.gyb", line 228, in bodyArgs
   list.append("stack.fetchTail(startingAt: " + str(p) + ")")
AttributeError: 'map' object has no attribute 'append'
Failed to expand gyb template