Add support for evaluating requirement markers

scripts/fixate-requirements.py

@@ -73,6 +73,8 @@
     # Do not error, as will only use on pip >= 20
     pass
 
+from packaging.requirements import Requirement
+
 
 def parse_args():
     parser = argparse.ArgumentParser(
@@ -190,6 +192,12 @@ def write_requirements(
             if not req.req:
                 continue
 
+        # If the requirement has markers, and they don't meet the
+        # current environment ignore this requirement
+        packaging_req = Requirement(req.requirement)
+        if packaging_req.marker and not packaging_req.marker.evaluate():
+            continue
+
         if project_name in fixedreq_hash:
             raise ValueError(
                 'Duplicate definition for dependency "%s"' % (project_name)