In build_meta, remove dependency on pkg_resources.

Author: jaraco

setuptools/build_meta.py

@@ -38,7 +38,7 @@
 import setuptools
 import distutils
 
-from pkg_resources import parse_requirements
+import setuptools.extern.jaraco.text as text
 
 __all__ = ['get_requires_for_build_sdist',
            'get_requires_for_build_wheel',
@@ -49,14 +49,23 @@
            'SetupRequirementsError']
 
 
+def parse_requirements(strs):
+    """
+    Yield requirement strings for each specification in `strs`.
+
+    `strs` must be a string, or a (possibly-nested) iterable thereof.
+    """
+    return text.join_continuation(map(text.drop_comment, text.yield_lines(strs)))
+
+
 class SetupRequirementsError(BaseException):
     def __init__(self, specifiers):
         self.specifiers = specifiers
 
 
 class Distribution(setuptools.dist.Distribution):
     def fetch_build_eggs(self, specifiers):
-        specifier_list = list(map(str, parse_requirements(specifiers)))
+        specifier_list = list(parse_requirements(specifiers))
 
         raise SetupRequirementsError(specifier_list)