old_contents: """
   mbed CMSIS-DAP debugger
   Copyright (c) 2012-2015 ARM Limited
  
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
  
       http://www.apache.org/licenses/LICENSE-2.0
  
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
  """
  
  from setuptools import setup, find_packages
  import sys
  
  # Common dependencies.
  install_requires = [
      'intelhex',
      'six',
      'enum34',
      'future',
      'websocket-client',
      'intervaltree',
      'colorama',
      'pyelftools',
      'pyusb>=1.0.0b2',
      ]
  
  # Add OS-specific dependencies.
  os_install_requires = {
      'linux' : [
          ],
      'win32' : [
          'pywinusb>=0.4.0',
          ],
      'darwin' : [
          'hidapi',
          ],
      }
  install_requires.extend(os_install_requires.get(sys.platform, []))
  
  setup(
      name="pyOCD",
      use_scm_version={
          'local_scheme': 'dirty-tag',
          'write_to': 'pyOCD/_version.py'
      },
      setup_requires=['setuptools_scm!=1.5.3,!=1.5.4', 'setuptools_scm_git_archive'],
      description="CMSIS-DAP debugger for Python",
      long_description=open('README.rst', 'r').read(),
      author="Chris Reed, Martin Kojtal, Russ Butler",
      author_email="chris.reed@arm.com, martin.kojtal@arm.com, russ.butler@arm.com",
      url='https://github.com/mbedmicro/pyOCD',
      license="Apache 2.0",
      install_requires=install_requires,
      classifiers=[
          "Development Status :: 4 - Beta",
          "License :: OSI Approved :: Apache Software License",
          "Programming Language :: Python",
          "Programming Language :: Python :: 2",
          "Programming Language :: Python :: 2.7",
          "Programming Language :: Python :: 3",
          "Programming Language :: Python :: 3.6",
      ],
      extras_require={
          'dissassembler': ['capstone']
      },
      entry_points={
          'console_scripts': [
              'pyocd-gdbserver = pyOCD.tools.gdb_server:main',
              'pyocd-flashtool = pyOCD.tools.flash_tool:main',
              'pyocd-tool = pyOCD.tools.pyocd:main',
          ],
      },
      packages=find_packages(),
      include_package_data=True,  # include files from MANIFEST.in
  )
  
new_contents: """
   mbed CMSIS-DAP debugger
   Copyright (c) 2012-2018 ARM Limited
  
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
  
       http://www.apache.org/licenses/LICENSE-2.0
  
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
  """
  
  from setuptools import setup, find_packages
  
  setup(
      name="pyOCD",
      use_scm_version={
          'local_scheme': 'dirty-tag',
          'write_to': 'pyOCD/_version.py'
      },
      setup_requires=[
          'setuptools_scm!=1.5.3,!=1.5.4',
          'setuptools_scm_git_archive'
      ],
      description="CMSIS-DAP debugger for Python",
      long_description=open('README.rst', 'r').read(),
      author="Chris Reed, Martin Kojtal, Russ Butler",
      author_email="chris.reed@arm.com, martin.kojtal@arm.com, russ.butler@arm.com",
      url='https://github.com/mbedmicro/pyOCD',
      license="Apache 2.0",
      install_requires = [
          'intelhex',
          'six',
          'enum34;python_version<"3.4"',
          'future',
          'websocket-client',
          'intervaltree',
          'colorama',
          'pyelftools',
          'pyusb>=1.0.0b2',
          'pywinusb>=0.4.0;platform_system=="Windows"',
          'hidapi;platform_system=="Darwin"'
          ],
      classifiers=[
          "Development Status :: 4 - Beta",
          "License :: OSI Approved :: Apache Software License",
          "Programming Language :: Python",
          "Programming Language :: Python :: 2",
          "Programming Language :: Python :: 2.7",
          "Programming Language :: Python :: 3",
          "Programming Language :: Python :: 3.6",
          "Programming Language :: Python :: 3.7",
      ],
      extras_require={
          'dissassembler': ['capstone']
      },
      entry_points={
          'console_scripts': [
              'pyocd-gdbserver = pyOCD.tools.gdb_server:main',
              'pyocd-flashtool = pyOCD.tools.flash_tool:main',
              'pyocd-tool = pyOCD.tools.pyocd:main',
          ],
      },
      packages=find_packages(),
      include_package_data=True,  # include files from MANIFEST.in
  )
  
subject: Change setup.py to use dependency markers.