Bug 1680802: Install pylint requirements with legacy resolver r=firefox-build-system-reviewers,sheehan,glandium

pylint_requirements.txt fail to install with the new pip resolver due
to a conflict between astroid and lazy-object-proxy.
Rather than bumping those packages and handling the potential fallout,
the package-upgrade has been deferred and we will use the legacy
resolver in the interrim.

Differential Revision: https://phabricator.services.mozilla.com/D99940

python/mach_commands.py

@@ -242,7 +242,11 @@ class MachCommands(MachCommandBase):
                 and test["requirements"] not in installed_requirements
             ):
                 self.virtualenv_manager.install_pip_requirements(
-                    test["requirements"], quiet=True
+                    test["requirements"],
+                    quiet=True,
+                    # pylint_requirements.txt must use the legacy resolver until bug 1682959
+                    # is resolved.
+                    legacy_resolver=True,
                 )
                 installed_requirements.add(test["requirements"])
 

python/mozbuild/mozbuild/virtualenv.py

@@ -619,7 +619,12 @@ class VirtualenvManager(VirtualenvHelper):
         return self._run_pip(args)
 
     def install_pip_requirements(
-        self, path, require_hashes=True, quiet=False, vendored=False
+        self,
+        path,
+        require_hashes=True,
+        quiet=False,
+        vendored=False,
+        legacy_resolver=False,
     ):
         """Install a pip requirements.txt file.
 
@@ -654,6 +659,9 @@ class VirtualenvManager(VirtualenvHelper):
                 ]
             )
 
+        if legacy_resolver:
+            args.append("--use-deprecated=legacy-resolver")
+
         return self._run_pip(args)
 
     def _run_pip(self, args):

tools/lint/python/pylint.py

@@ -51,7 +51,11 @@ def setup(root, **lintargs):
     virtualenv_manager = lintargs["virtualenv_manager"]
     try:
         virtualenv_manager.install_pip_requirements(
-            PYLINT_REQUIREMENTS_PATH, quiet=True
+            PYLINT_REQUIREMENTS_PATH,
+            quiet=True,
+            # The defined versions of astroid and lazy-object-proxy conflict and fail to
+            # install with the new 2020 pip resolver (bug 1682959)
+            legacy_resolver=True,
         )
     except subprocess.CalledProcessError:
         print(PYLINT_INSTALL_ERROR)