Fix installation of packages with the --no-dev option

poetry/installation/installer.py

@@ -167,9 +167,7 @@ class Installer:
         else:
             self._io.writeln('<info>Installing dependencies from lock file</>')
 
-            locked_repository = self._locker.locked_repository(
-                self.is_dev_mode()
-            )
+            locked_repository = self._locker.locked_repository(True)
 
             if not self._locker.is_fresh():
                 self._io.writeln(
@@ -475,6 +473,11 @@ class Installer:
                 if package.name not in extra_packages:
                     op.skip('Not required')
 
+            # If the package is a dev package and dev packages
+            # are not requests, we skip it
+            if package.category == 'dev' and not self.is_dev_mode():
+                op.skip('Dev dependencies not requested')
+
     def _get_extra_packages(self, repo):
         """
         Returns all packages required by extras.