git: don't allow to delete a protected remote branch: IDEA-194090

plugins/git4idea/src/git4idea/GitProtectedBranches.kt

@@ -22,6 +22,15 @@ fun findProtectedRemoteBranch(repository: GitRepository, branches: Collection<St
     firstOrNull { branches.contains(it) }
 }
 
+/**
+ * Checks if the given remote branch is protected.
+ *
+ * @param branchName the name of the remote branch in the "local" format, e.g. `origin/master`
+ */
+fun isRemoteBranchProtected(repositories: Collection<GitRepository>, branchName: String): Boolean {
+  return repositories.any { findProtectedRemoteBranch(it, listOf(branchName)) != null }
+}
+
 fun findProtectedRemoteBranchContainingCommit(repository: GitRepository, hash: Hash): String? {
   val root = repository.root
   val branchesGetter = VcsProjectLog.getInstance(repository.project).dataManager?.containingBranchesGetter

plugins/git4idea/src/git4idea/ui/branch/GitBranchPopupActions.java

@@ -29,6 +29,7 @@ import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.util.ui.EmptyIcon;
 import git4idea.GitBranch;
 import git4idea.GitLocalBranch;
+import git4idea.GitProtectedBranchesKt;
 import git4idea.actions.GitAbstractRebaseAction;
 import git4idea.branch.*;
 import git4idea.config.GitVcsSettings;
@@ -518,6 +519,11 @@ class GitBranchPopupActions {
         brancher.deleteRemoteBranch(myBranchName, myRepositories);
         reportUsage(myProject, "git.branch.delete.remote");
       }
+
+      @Override
+      public void update(AnActionEvent e) {
+        e.getPresentation().setEnabled(!GitProtectedBranchesKt.isRemoteBranchProtected(myRepositories, myBranchName));
+      }
     }
   }