Fix some issues found by lgtm.com

* This import of module shutil is redundant, as it was previously imported on line 35.
* Testing for None should use the 'is' operator.
* The value assigned to local variable 'hno' is never used.

Author: misery

patch.py

@@ -368,7 +368,7 @@ def lineno(self):
             header.append(fe.line)
             fe.next()
         if fe.is_empty:
-            if p == None:
+            if p is None:
               debug("no patch data found")  # error is shown later
               self.errors += 1
             else:
@@ -941,7 +941,6 @@ def apply(self, strip=0, root=None):
         if exists(backupname):
           warning("can't backup original file to %s - aborting" % backupname)
         else:
-          import shutil
           shutil.move(filename, backupname)
           if self.write_hunks(backupname, filename, p.hunks):
             info("successfully patched %d/%d:\t %s" % (i+1, total, filename))
@@ -1005,7 +1004,6 @@ class NoMatch(Exception):
 
     lineno = 1
     line = fp.readline()
-    hno = None
     try:
       for hno, h in enumerate(hunks):
         # skip to first line of the hunk