Move mac arch calculation to separate function

Author: chrahunt

src/pip/_internal/pep425tags.py

@@ -261,6 +261,25 @@ def get_all_minor_versions_as_strings(version_info):
     return versions
 
 
+def _mac_platforms(arch):
+    # type: (str) -> List[str]
+    match = _osx_arch_pat.match(arch)
+    if match:
+        name, major, minor, actual_arch = match.groups()
+        mac_version = (int(major), int(minor))
+        mac_arches = list(mac_platforms(mac_version, actual_arch))
+        arches = [
+            # Technically a user could've passed something only
+            # starting with 'macosx', not necessarily macosx_.
+            '{}_{}'.format(name, arch[len('macosx_'):])
+            for arch in mac_arches
+        ]
+    else:
+        # arch pattern didn't match (?!)
+        arches = [arch]
+    return arches
+
+
 def get_supported(
     version=None,  # type: Optional[str]
     platform=None,  # type: Optional[str]
@@ -311,20 +330,7 @@ def get_supported(
     arch = platform or get_platform()
     arch_prefix, arch_sep, arch_suffix = arch.partition('_')
     if arch.startswith('macosx'):
-        match = _osx_arch_pat.match(arch)
-        if match:
-            name, major, minor, actual_arch = match.groups()
-            mac_version = (int(major), int(minor))
-            mac_arches = list(mac_platforms(mac_version, actual_arch))
-            arches = [
-                # Technically a user could've passed something only
-                # starting with 'macosx', not necessarily macosx_.
-                '{}_{}'.format(name, arch[len('macosx_'):])
-                for arch in mac_arches
-            ]
-        else:
-            # arch pattern didn't match (?!)
-            arches = [arch]
+        arches = _mac_platforms(arch)
     elif arch_prefix == 'manylinux2014':
         arches = [arch]
         # manylinux1/manylinux2010 wheels run on most manylinux2014 systems