[commands/cache] Minor clean-up.

- Consistently use singular 'cache' (not plural 'caches').
- Remove unnecessary uses of the word 'currently'.
- Use 'file(s)' instead of 'files', to account for case of only one file.
- Use .format() when appropriate.
- Minor cleanup of `pip cache`-related files in docs/.

docs/html/reference/pip_cache.rst

@@ -2,7 +2,7 @@
 .. _`pip cache`:
 
 pip cache
-------------
+---------
 
 .. contents::
 

docs/man/commands/cache.rst

@@ -1,8 +1,8 @@
 :orphan:
 
-==========
+=========
 pip-cache
-==========
+=========
 
 Description
 ***********

src/pip/_internal/commands/__init__.py

@@ -66,7 +66,7 @@ commands_dict = OrderedDict([
     )),
     ('cache', CommandInfo(
         'pip._internal.commands.cache', 'CacheCommand',
-        "Inspect and manage pip's caches.",
+        "Inspect and manage pip's cache.",
     )),
     ('wheel', CommandInfo(
         'pip._internal.commands.wheel', 'WheelCommand',

src/pip/_internal/commands/cache.py

@@ -20,12 +20,12 @@ logger = logging.getLogger(__name__)
 
 class CacheCommand(Command):
     """
-        Inspect and manage pip's caches.
+        Inspect and manage pip's cache.
 
         Subcommands:
 
         info:
-            Show information about the caches.
+            Show information about the cache.
         list:
             List filenames of packages stored in the cache.
         remove:
@@ -107,7 +107,7 @@ class CacheCommand(Command):
         files = self._find_wheels(options, pattern)
 
         if not files:
-            logger.info('Nothing is currently cached.')
+            logger.info('Nothing cached.')
             return
 
         results = []
@@ -115,7 +115,7 @@ class CacheCommand(Command):
             wheel = os.path.basename(filename)
             size = filesystem.friendly_file_size(filename)
             results.append(' - {} ({})'.format(wheel, size))
-        logger.info('Current cache contents:\n')
+        logger.info('Cache contents:\n')
         logger.info('\n'.join(sorted(results)))
 
     def remove_cache_items(self, options, args):
@@ -133,7 +133,7 @@ class CacheCommand(Command):
         for filename in files:
             os.unlink(filename)
             logger.debug('Removed %s', filename)
-        logger.info('Removed %s files', len(files))
+        logger.info('Removed %s file(s)', len(files))
 
     def purge_cache(self, options, args):
         # type: (Values, List[Any]) -> None

tests/functional/test_cache.py

@@ -15,7 +15,7 @@ def test_cache_info(script, monkeypatch):
     result = script.pip('cache', 'info')
     cache_dir = _cache_dir(script)
 
-    assert 'Location: %s' % cache_dir in result.stdout
+    assert 'Location: {}'.format(cache_dir) in result.stdout
     # TODO(@duckinator): This should probably test that the number of
     #   packages is actually correct, but I'm not sure how to do that
     #   without pretty much re-implementing the entire cache info command.