Add FF to force JGit-based Git backend

Author: henrymercer

lib/entry-points.js

@@ -82,6 +82,11 @@ export enum Feature {
   DisableJavaBuildlessEnabled = "disable_java_buildless_enabled",
   DisableKotlinAnalysisEnabled = "disable_kotlin_analysis_enabled",
   ExportDiagnosticsEnabled = "export_diagnostics_enabled",
+  /**
+   * Emergency override that forces the CodeQL CLI to use the JGit-based Git backend instead of its
+   * default backend selection.
+   */
+  ForceJGit = "force_jgit",
   ForceNightly = "force_nightly",
   IgnoreGeneratedFiles = "ignore_generated_files",
   JavaNetworkDebugging = "java_network_debugging",
@@ -224,6 +229,11 @@ export const featureConfig = {
     legacyApi: true,
     minimumVersion: undefined,
   },
+  [Feature.ForceJGit]: {
+    defaultValue: false,
+    envVar: "CODEQL_ACTION_FORCE_JGIT",
+    minimumVersion: undefined,
+  },
   [Feature.ForceNightly]: {
     defaultValue: false,
     envVar: "CODEQL_ACTION_FORCE_NIGHTLY",

src/feature-flags.ts

@@ -614,6 +614,11 @@ async function run(startedAt: Date) {
       core.exportVariable("CODEQL_EXTRACTOR_JAVA_AGENT_DISABLE_KOTLIN", "true");
     }
 
+    // Emergency override to force the CodeQL CLI back to the JGit-based Git backend.
+    if (await features.getValue(Feature.ForceJGit)) {
+      core.exportVariable("CODEQL_GIT_BACKEND", "jgit");
+    }
+
     const kotlinLimitVar =
       "CODEQL_EXTRACTOR_KOTLIN_OVERRIDE_MAXIMUM_VERSION_LIMIT";
     if (