Fix debug logging in release (#613)

debug_build was enabled for users who were using
`--compilation_mode=dbg`, which lead to `set -x` being set in the
terminal used to create the venv, and tons of logging users don't need
to see. The help for the venv tool was also printed.

Replaces #596 which has conflicts.

### Changes are visible to end-users: yes

- Searched for relevant documentation and updated as needed: yes/no
- Breaking change (forces users to change their own code or config):
yes/no
- Suggested release notes appear below: yes/no

### Test plan

- Covered by existing test cases
- New test cases added
- Manual testing; please provide instructions so we can reproduce:

Co-authored-by: Keith Smiley <[email protected]>

Author: arrdem

py/private/py_venv/BUILD.bazel

@@ -1,4 +1,5 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+load("@bazel_skylib//rules:common_settings.bzl", "bool_flag")
 load(":defs.bzl", "py_venv_test")
 
 package(default_visibility = [
@@ -11,10 +12,15 @@ exports_files([
     "link.py",
 ])
 
+bool_flag(
+    name = "debug_venv",
+    build_setting_default = False,
+)
+
 config_setting(
-    name = "debug_build",
-    values = {
-        "compilation_mode": "dbg",
+    name = "debug_venv_setting",
+    flag_values = {
+        ":debug_venv": "True",
     },
 )
 

py/private/py_venv/link.py

@@ -46,9 +46,7 @@ def munge_venv_name(target_package, virtualenv_name):
         default=munge_venv_name(target_package, virtualenv_name),
         help="Name to link the virtualenv as.",
     )
-
 
-    PARSER.print_help(sys.stdout)
     opts = PARSER.parse_args()
     dest = Path(os.path.join(opts.dest, opts.name))
     print("""
@@ -68,7 +66,7 @@ def munge_venv_name(target_package, virtualenv_name):
             dest.unlink()
         except FileNotFoundError:
             pass
-    
+
         # From -> to
         dest.symlink_to(virtualenv_home, target_is_directory=True)
         print("Link created!")

py/private/py_venv/py_venv.bzl

@@ -351,7 +351,7 @@ _py_venv = rule(
 
 def _wrap_with_debug(rule):
     def helper(**kwargs):
-        kwargs["debug"] = select({Label(":debug_build"): True, "//conditions:default": False})
+        kwargs["debug"] = select({Label(":debug_venv_setting"): True, "//conditions:default": False})
         return rule(**kwargs)
 
     return helper
@@ -383,7 +383,7 @@ def py_venv_link(venv_name = None, srcs = [], **kwargs):
 
     # Note that the binary is already wrapped with debug
     link_script = str(Label("//py/private/py_venv:link.py"))
-    kwargs["debug"] = select({Label(":debug_build"): True, "//conditions:default": False})
+    kwargs["debug"] = select({Label(":debug_venv_setting"): True, "//conditions:default": False})
     py_venv_binary(
         args = [] + (["--name=" + venv_name] if venv_name else []),
         main = link_script,