Merge pull request #16490 from boegel/20221025215535_new_pr_Python2716

work around installation problem for extensions in Python 2.7.16 easyconfig due to missing build-backend spec in pyproject.toml

easybuild/easyconfigs/p/Python/Python-2.7.16-GCCcore-8.3.0.eb

@@ -37,6 +37,11 @@ exts_default_options = {
     'sanity_pip_check': True,
 }
 
+# workaround for: AttributeError: 'module' object has no attribute '__legacy__'
+# see also https://github.com/pypa/pip/issues/6264
+local_fix_pyproject_toml_cmd = """sed -i 's/\(\[build-system\]\)/\\1\\nbuild-backend="setuptools.build_meta"/g' """
+local_fix_pyproject_toml_cmd += "pyproject.toml && "
+
 # order is important!
 # package versions updated Sept 13th 2019
 exts_list = [
@@ -125,6 +130,7 @@ exts_list = [
     ('PyNaCl', '1.3.0', {
         'modulename': 'nacl',
         'checksums': ['0c6100edd16fefd1557da078c7a31e7b7d7a52ce39fdca2bec29d4f7b6e7600c'],
+        'preinstallopts': local_fix_pyproject_toml_cmd,
     }),
     ('bcrypt', '3.1.7', {
         'checksums': ['0b0069c752ec14172c5f78208f1863d7ad6755a6fae6fe76ec2c80d13be41e42'],
@@ -209,9 +215,11 @@ exts_list = [
     }),
     ('importlib_metadata', '0.22', {
         'checksums': ['652234b6ab8f2506ae58e528b6fbcc668831d3cc758e1bc01ef438d328b68cdb'],
+        'preinstallopts': local_fix_pyproject_toml_cmd,
     }),
     ('pluggy', '0.13.0', {
         'checksums': ['fa5fa1622fa6dd5c030e9cad086fa19ef6a0cf6d7a2d12318e10cb49d6d68f34'],
+        'preinstallopts': local_fix_pyproject_toml_cmd,
     }),
     # more-itertools 5.0.0 is the most recent version still supporting Python 2.x
     ('more-itertools', '5.0.0', {