Clean up byte-compilation code in packaging (#11254 followup).

- Don't use keyword arguments for debug_override; I find it more
  readable to have a comment explaining that True makes pyc and False
  pyo than to write out the non-obvious (when you haven’t read the doc)
  argument name

- Move duplicate code from build_py and install_lib into cmd

- Remove obsolete verbose argument of util.byte_compile

- Remove obsolete passing of -O/-OO to the Python process spawned by
  util.byte_compile (I’ll remove the whole spawning later, after I write
  more tests to check the contents of pyc and pyo files; now that
  byte_compile does not depend on the value of __debug__ in the calling
  Python, we can call py_compile or compileall directly)

Lib/packaging/util.py

@@ -296,7 +296,7 @@ def strtobool(val):
 
 
 def byte_compile(py_files, optimize=0, force=False, prefix=None,
-                 base_dir=None, verbose=0, dry_run=False, direct=None):
+                 base_dir=None, dry_run=False, direct=None):
     """Byte-compile a collection of Python source files to either .pyc
     or .pyo files in a __pycache__ subdirectory.
 
@@ -305,6 +305,9 @@ def byte_compile(py_files, optimize=0, force=False, prefix=None,
       0 - don't optimize (generate .pyc)
       1 - normal optimization (like "python -O")
       2 - extra optimization (like "python -OO")
+    This function is independent from the running Python's -O or -B options;
+    it is fully controlled by the parameters passed in.
+
     If 'force' is true, all files are recompiled regardless of
     timestamps.
 
@@ -325,10 +328,9 @@ def byte_compile(py_files, optimize=0, force=False, prefix=None,
     the source for details).  The 'direct' flag is used by the script
     generated in indirect mode; unless you know what you're doing, leave
     it set to None.
-
-    This function is independent from the running Python's -O or -B options;
-    it is fully controlled by the parameters passed in.
     """
+    # FIXME use compileall + remove direct/indirect shenanigans
+
     # First, if the caller didn't force us into direct or indirect mode,
     # figure out which mode we should be in.  We take a conservative
     # approach: choose direct mode *only* if the current interpreter is
@@ -381,15 +383,11 @@ files = [
                 script.write("""
 byte_compile(files, optimize=%r, force=%r,
              prefix=%r, base_dir=%r,
-             verbose=%r, dry_run=False,
+             dry_run=False,
              direct=True)
-""" % (optimize, force, prefix, base_dir, verbose))
+""" % (optimize, force, prefix, base_dir))
 
         cmd = [sys.executable, script_name]
-        if optimize == 1:
-            cmd.insert(1, "-O")
-        elif optimize == 2:
-            cmd.insert(1, "-OO")
 
         env = os.environ.copy()
         env['PYTHONPATH'] = os.path.pathsep.join(sys.path)
@@ -415,8 +413,10 @@ byte_compile(files, optimize=%r, force=%r,
             # Terminology from the py_compile module:
             #   cfile - byte-compiled file
             #   dfile - purported source filename (same as 'file' by default)
-            debug_override = not optimize
-            cfile = imp.cache_from_source(file, debug_override)
+            # The second argument to cache_from_source forces the extension to
+            # be .pyc (if true) or .pyo (if false); without it, the extension
+            # would depend on the calling Python's -O option
+            cfile = imp.cache_from_source(file, not optimize)
             dfile = file
 
             if prefix:
@@ -1334,7 +1334,7 @@ def copy_tree(src, dst, preserve_mode=True, preserve_times=True,
               preserve_symlinks=False, update=False, verbose=True,
               dry_run=False):
     # FIXME use of this function is why we get spurious logging message on
-    # stdout when tests run; kill and replace by shuil!
+    # stdout when tests run; kill and replace by shutil!
     from distutils.file_util import copy_file
 
     if not dry_run and not os.path.isdir(src):
@@ -1448,8 +1448,7 @@ def encode_multipart(fields, files, boundary=None):
 
     Returns (content_type: bytes, body: bytes) ready for http.client.HTTP.
     """
-    # Taken from
-    # http://code.activestate.com/recipes/146306-http-client-to-post-using-multipartform-data/
+    # Taken from http://code.activestate.com/recipes/146306
 
     if boundary is None:
         boundary = b'--------------GHSKFJDLGDS7543FJKLFHRE75642756743254'