style: ensure that all packages pass spack style -a

- fix trailing whitespace and other issues uncovered by better flake8
  checking.

- fix extra whitespace printed by `spack style` command

lib/spack/spack/cmd/info.py

@@ -111,7 +111,7 @@ def lines(self):
             yield '    None'
         else:
             yield '    ' + self.fmt % self.headers
-            underline = tuple([l * "=" for l in self.column_widths])
+            underline = tuple([w * "=" for w in self.column_widths])
             yield '    ' + self.fmt % underline
             yield ''
             for k, v in sorted(self.variants.items()):

lib/spack/spack/cmd/style.py

@@ -183,6 +183,8 @@ def cwd_relative(path):
             )
 
         for line in output.split("\n"):
+            if not line:
+                continue
             print(
                 re_obj.sub(
                     cwd_relative,

lib/spack/spack/test/cmd/dependencies.py

@@ -51,8 +51,11 @@ def test_direct_installed_dependencies(mock_packages, database):
     with color_when(False):
         out = dependencies('--installed', 'mpileaks^mpich')
 
-    lines = [l for l in out.strip().split('\n') if not l.startswith('--')]
-    hashes = set([re.split(r'\s+', l)[0] for l in lines])
+    lines = [
+        line for line in out.strip().split('\n')
+        if not line.startswith('--')
+    ]
+    hashes = set([re.split(r'\s+', line)[0] for line in lines])
 
     expected = set([spack.store.db.query_one(s).dag_hash(7)
                     for s in ['mpich', 'callpath^mpich']])
@@ -65,8 +68,11 @@ def test_transitive_installed_dependencies(mock_packages, database):
     with color_when(False):
         out = dependencies('--installed', '--transitive', 'mpileaks^zmpi')
 
-    lines = [l for l in out.strip().split('\n') if not l.startswith('--')]
-    hashes = set([re.split(r'\s+', l)[0] for l in lines])
+    lines = [
+        line for line in out.strip().split('\n')
+        if not line.startswith('--')
+    ]
+    hashes = set([re.split(r'\s+', line)[0] for line in lines])
 
     expected = set([spack.store.db.query_one(s).dag_hash(7)
                     for s in ['zmpi', 'callpath^zmpi', 'fake',