`pip wheel` needs --src option if it's going support --editable for vcs reqs

pip/cmdoptions.py

@@ -9,7 +9,7 @@ pass on state. To be consistent, all options will follow this design.
 """
 import copy
 from optparse import OptionGroup, SUPPRESS_HELP, Option
-from pip.locations import build_prefix, default_log_file
+from pip.locations import build_prefix, default_log_file, src_prefix
 
 
 def make_option_group(group, parser):
@@ -296,6 +296,16 @@ editable = OptionMaker(
           '"develop mode") from a local project path or a VCS url.'),
 )
 
+src = OptionMaker(
+    '--src', '--source', '--source-dir', '--source-directory',
+    dest='src_dir',
+    metavar='dir',
+    default=src_prefix,
+    help='Directory to check out editable projects into. '
+    'The default in a virtualenv is "<venv path>/src". '
+    'The default for global installs is "<current dir>/src".'
+)
+
 use_wheel = OptionMaker(
     '--use-wheel',
     dest='use_wheel',

pip/commands/install.py

@@ -4,7 +4,7 @@ import shutil
 
 from pip.req import InstallRequirement, RequirementSet, parse_requirements
 from pip.log import logger
-from pip.locations import (src_prefix, virtualenv_no_global, distutils_scheme,
+from pip.locations import (virtualenv_no_global, distutils_scheme,
                            build_prefix)
 from pip.basecommand import Command
 from pip.index import PackageFinder
@@ -64,15 +64,7 @@ class InstallCommand(Command):
         )
 
         cmd_opts.add_option(cmdoptions.download_cache.make())
-
-        cmd_opts.add_option(
-            '--src', '--source', '--source-dir', '--source-directory',
-            dest='src_dir',
-            metavar='dir',
-            default=src_prefix,
-            help='Directory to check out editable projects into. '
-            'The default in a virtualenv is "<venv path>/src". '
-            'The default for global installs is "<current dir>/src".')
+        cmd_opts.add_option(cmdoptions.src.make())
 
         cmd_opts.add_option(
             '-U', '--upgrade',

pip/commands/wheel.py

@@ -64,6 +64,7 @@ class WheelCommand(Command):
         cmd_opts.add_option(cmdoptions.editable.make())
         cmd_opts.add_option(cmdoptions.requirements.make())
         cmd_opts.add_option(cmdoptions.download_cache.make())
+        cmd_opts.add_option(cmdoptions.src.make())
         cmd_opts.add_option(cmdoptions.no_deps.make())
         cmd_opts.add_option(cmdoptions.build_dir.make())
 
@@ -159,7 +160,7 @@ class WheelCommand(Command):
         options.build_dir = os.path.abspath(options.build_dir)
         requirement_set = RequirementSet(
             build_dir=options.build_dir,
-            src_dir=None,
+            src_dir=options.src_dir,
             download_dir=None,
             download_cache=options.download_cache,
             ignore_dependencies=options.ignore_dependencies,