bazel: Set --incompatible_default_to_explicit_init_py

Bug: b/266950138
Change-Id: Ifc643a01ddc49e77c6180711ec73e73911e4740c
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/180454
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Pigweed-Auto-Submit: Ted Pudlik <tpudlik@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>

.bazelrc

@@ -19,6 +19,15 @@
 common --per_file_copt=external/.*@-w
 common --host_per_file_copt=external/.*@-w
 
+# Don't automatically create __init__.py files.
+#
+# This prevents spurious package name collisions at import time, and should be
+# the default (https://github.com/bazelbuild/bazel/issues/7386). It's
+# particularly helpful for Pigweed, because we have many potential package name
+# collisions due to a profusion of stuttering paths like
+# pw_transfer/py/pw_transfer.
+common --incompatible_default_to_explicit_init_py
+
 # Required for new toolchain resolution API.
 build --incompatible_enable_cc_toolchain_resolution