spack flake8 should exempt line-wrapped directives (#3990)

- Omit final paren from regular expressions in cmd/flake8.py
- Allows long directives to be exempted even if they are wrapped.

lib/spack/spack/cmd/flake8.py

@@ -58,14 +58,14 @@
             r'^\s*svn\s*=',
             r'^\s*hg\s*=',
             r'^\s*list_url\s*=',
-            r'^\s*version\(.*\)',
-            r'^\s*variant\(.*\)',
-            r'^\s*provides\(.*\)',
-            r'^\s*extends\(.*\)',
-            r'^\s*depends_on\(.*\)',
-            r'^\s*conflicts\(.*\)',
-            r'^\s*resource\(.*\)',
-            r'^\s*patch\(.*\)',
+            r'^\s*version\(',
+            r'^\s*variant\(',
+            r'^\s*provides\(',
+            r'^\s*extends\(',
+            r'^\s*depends_on\(',
+            r'^\s*conflicts\(',
+            r'^\s*resource\(',
+            r'^\s*patch\(',
         ],
         # Exempt '@when' decorated functions from redefinition errors.
         'F811': [