Revert unneccessary changes made in bpo-30296 and apply other improvements. (GH-2624)

(cherry picked from commit 3f2e6f15)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Lib/logging/config.py

@@ -460,7 +460,7 @@ class BaseConfigurator(object):
             c = self.resolve(c)
         props = config.pop('.', None)
         # Check for valid identifiers
-        kwargs = dict((k, config[k]) for k in config if valid_ident(k))
+        kwargs = {k: config[k] for k in config if valid_ident(k)}
         result = c(**kwargs)
         if props:
             for name, value in props.items():
@@ -723,7 +723,7 @@ class DictConfigurator(BaseConfigurator):
                 config['address'] = self.as_tuple(config['address'])
             factory = klass
         props = config.pop('.', None)
-        kwargs = dict((k, config[k]) for k in config if valid_ident(k))
+        kwargs = {k: config[k] for k in config if valid_ident(k)}
         try:
             result = factory(**kwargs)
         except TypeError as te:

Lib/pstats.py

@@ -530,7 +530,7 @@ def add_callers(target, source):
         if func in new_callers:
             if isinstance(caller, tuple):
                 # format used by cProfile
-                new_callers[func] = tuple(i[0] + i[1] for i in zip(caller, new_callers[func]))
+                new_callers[func] = tuple(i + j for i, j in zip(caller, new_callers[func]))
             else:
                 # format used by profile
                 new_callers[func] += caller

Lib/turtle.py

@@ -3839,7 +3839,7 @@ def write_docstringdict(filename="turtle_docstringdict"):
         docsdict[key] = eval(key).__doc__
 
     with open("%s.py" % filename,"w") as f:
-        keys = sorted(x for x in docsdict.keys()
+        keys = sorted(x for x in docsdict
                       if x.split('.')[1] not in _alias_list)
         f.write('docsdict = {\n\n')
         for key in keys[:-1]:

Lib/urllib/request.py

@@ -1286,7 +1286,8 @@ class AbstractHTTPHandler(BaseHandler):
         h.set_debuglevel(self._debuglevel)
 
         headers = dict(req.unredirected_hdrs)
-        headers.update((k, v) for k, v in req.headers.items() if k not in headers)
+        headers.update({k: v for k, v in req.headers.items()
+                        if k not in headers})
 
         # TODO(jhylton): Should this be redesigned to handle
         # persistent connections?