Fix flake8 errors related to lines

Fixed the flake 8 errors that involved too many blank lines or not
enough blank lines. Basically, all of the flake8 errors except line
length errors.

lib/spack/spack/stage.py

@@ -144,7 +144,6 @@ def __init__(self, url_or_fetch_strategy,
         # Flag to decide whether to delete the stage folder on exit or not
         self.keep = keep
 
-
     def __enter__(self):
         """
         Entering a stage context will create the stage directory
@@ -155,7 +154,6 @@ def __enter__(self):
         self.create()
         return self
 
-
     def __exit__(self, exc_type, exc_val, exc_tb):
         """
         Exiting from a stage context will delete the stage directory unless:
@@ -174,7 +172,6 @@ def __exit__(self, exc_type, exc_val, exc_tb):
         if exc_type is None and not self.keep:
             self.destroy()
 
-
     def _need_to_create_path(self):
         """Makes sure nothing weird has happened since the last time we
            looked at path.  Returns True if path already exists and is ok.
@@ -334,7 +331,6 @@ def fetch(self, mirror_only=False):
             self.fetcher = self.default_fetcher
             raise fs.FetchError(errMessage, None)
 
-
     def check(self):
         """Check the downloaded archive against a checksum digest.
            No-op if this stage checks code out of a repository."""
@@ -348,11 +344,9 @@ def check(self):
         else:
             self.fetcher.check()
 
-
     def cache_local(self):
         spack.cache.store(self.fetcher, self.mirror_path)
 
-
     def expand_archive(self):
         """Changes to the stage directory and attempt to expand the downloaded
            archive.  Fail if the stage is not set up or if the archive is not yet
@@ -509,8 +503,11 @@ def chdir(self):
             raise ChdirError("Setup failed: no such directory: " + self.path)
 
     # DIY stages do nothing as context managers.
-    def __enter__(self): pass
-    def __exit__(self, exc_type, exc_val, exc_tb): pass
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
 
     def chdir_to_source(self):
         self.chdir()