--normalize-modules insert underscore in the module decl but not in the filename

[ghost]

mkdir test && echo "" > test/TestOne.h &&  dstep test/TestOne.h --normalize-modules=true --package=test
grep module "test/TestOne.d" module test.test_one

module test.test_one;

"TestOne.d" should be named "test_one.d" to match the module declaration. Problems arise when using generated binding with dub build --combined.