Flip --incompatible_allow_python_version_transitions

    With this flag enabled by default, the Python version is no longer "sticky" and forced to a fixed value by a command line flag. Instead it adjusts to whatever the `py_binary` or `py_test` declares its version to be.

    For more information see feature tracking issue #6583 and flag migration tracking issue #7307.

    Closes #7307.

    RELNOTES[INC]: (Python rules) The python version now changes to whatever version is specified in a `py_binary` or `py_test`'s `python_version` attribute, instead of being forced to the value set by a command line flag. You can temporarily revert this change with `--incompatible_allow_python_version_transitions=false`. See [#7307](bazelbuild/bazel#7307) for more information.

    PiperOrigin-RevId: 240227319

dataset/GitHub_Java/bazelbuild.bazel/src/main/java/com/google/devtools/build/lib/rules/python/PythonOptions.java

@@ -105,7 +105,7 @@ public String getTypeDescription() {
    */
   @Option(
       name = "incompatible_py3_is_default",
-      defaultValue = "true",
+      defaultValue = "false",
       documentationCategory = OptionDocumentationCategory.GENERIC_INPUTS,
       effectTags = {
         OptionEffectTag.LOADING_AND_ANALYSIS,
@@ -125,7 +125,7 @@ public String getTypeDescription() {
 
   @Option(
       name = "incompatible_py2_outputs_are_suffixed",
-      defaultValue = "true",
+      defaultValue = "false",
       documentationCategory = OptionDocumentationCategory.GENERIC_INPUTS,
       effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
       metadataTags = {
@@ -230,14 +230,11 @@ public String getTypeDescription() {
   public boolean incompatibleDisallowLegacyPyProvider;
 
   @Option(
-      name = "incompatible_use_python_toolchains",
+      // TODO(brandjon): Rename to --incompatible_use_python_toolchains when ready to make available
+      name = "experimental_use_python_toolchains",
       defaultValue = "false",
       documentationCategory = OptionDocumentationCategory.GENERIC_INPUTS,
       effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS},
-      metadataTags = {
-        OptionMetadataTag.INCOMPATIBLE_CHANGE,
-        OptionMetadataTag.TRIGGERED_BY_ALL_INCOMPATIBLE_CHANGES
-      },
       help =
           "If set to true, executable native Python rules will use the Python runtime specified by "
               + "the Python toolchain, rather than the runtime given by legacy flags like "
@@ -254,26 +251,6 @@ public String getTypeDescription() {
               + "data runfiles of another binary.")
   public boolean buildTransitiveRunfilesTrees;
 
-  @Option(
-      name = "incompatible_windows_escape_python_args",
-      defaultValue = "false",
-      documentationCategory = OptionDocumentationCategory.OUTPUT_PARAMETERS,
-      effectTags = {
-        OptionEffectTag.ACTION_COMMAND_LINES,
-        OptionEffectTag.AFFECTS_OUTPUTS,
-      },
-      metadataTags = {
-        OptionMetadataTag.INCOMPATIBLE_CHANGE,
-        OptionMetadataTag.TRIGGERED_BY_ALL_INCOMPATIBLE_CHANGES
-      },
-      help =
-          "On Linux/macOS/non-Windows: no-op. On Windows: this flag affects how py_binary and"
-              + " py_test targets are built: how their launcher escapes command line flags. When"
-              + " this flag is true, the launcher escapes command line flags using Windows-style"
-              + " escaping (correct behavior). When the flag is false, the launcher uses Bash-style"
-              + " escaping (buggy behavior). See https://github.com/bazelbuild/bazel/issues/7958")
-  public boolean windowsEscapePythonArgs;
-
   @Override
   public Map<OptionDefinition, SelectRestriction> getSelectRestrictions() {
     // TODO(brandjon): Instead of referencing the python_version target, whose path depends on the
@@ -392,11 +369,6 @@ public FragmentOptions getHost() {
     hostPythonOptions.buildPythonZip = buildPythonZip;
     hostPythonOptions.incompatibleDisallowLegacyPyProvider = incompatibleDisallowLegacyPyProvider;
     hostPythonOptions.incompatibleUsePythonToolchains = incompatibleUsePythonToolchains;
-    hostPythonOptions.windowsEscapePythonArgs = windowsEscapePythonArgs;
-
-    // Save host options in case of a further exec->host transition.
-    hostPythonOptions.hostForcePython = hostForcePython;
-
     return hostPythonOptions;
   }