fix(git): keep the branch name when breaking out of a failed rebase

When a pull with rebase stops on a conflict, HEAD is detached and
getCurrentBranch() returned null. "Abort rebase and push new branch"
then pushed the local commits to "conflicting-null-<time>" and failed
to switch back with "Branch name <null> is not allowed", leaving the
repository on the conflict branch.

Fall back to the branch JGit records in rebase-merge/head-name (or
rebase-apply/head-name) while a rebase is in progress. Found while
driving the conflict flow on an emulator against the e2e test server;
verified there: the edit is pushed to conflicting-master-<time> and the
operation completes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 43 insertions, 2 deletions

diff --git a/app/src/main/java/app/passwordstore/data/repo/PasswordRepository.kt b/app/src/main/java/app/passwordstore/data/repo/PasswordRepository.kt
index 71d771e1..7287044e 100644
--- a/app/src/main/java/app/passwordstore/data/repo/PasswordRepository.kt
+++ b/app/src/main/java/app/passwordstore/data/repo/PasswordRepository.kt
@@ -130,7 +130,10 @@ object PasswordRepository {
     return repository
   }
 
-  /** Get the currently checked out branch. */
+  /**
+   * Get the currently checked out branch. While a rebase is stopped HEAD is detached, so this
+   * returns the branch being rebased instead.
+   */
   fun getCurrentBranch(): String? {
     val repository = repository ?: return null
     val headRef = repository.findRef(Constants.HEAD) ?: return null
@@ -138,10 +141,20 @@ object PasswordRepository {
       val branchName = headRef.target.name
       Repository.shortenRefName(branchName)
     } else {
-      null
+      rebasedBranch(repository.directory)
     }
   }
 
+  /** Branch recorded by an in-progress rebase in [gitDir], or null when no rebase is running. */
+  fun rebasedBranch(gitDir: File): String? =
+    listOf("rebase-merge", "rebase-apply")
+      .map { gitDir.resolve(it).resolve("head-name") }
+      .firstOrNull { it.isFile }
+      ?.readText()
+      ?.trim()
+      ?.takeIf { it.startsWith(Constants.R_HEADS) }
+      ?.let(Repository::shortenRefName)
+
   /**
    * Gets the .gpg files in a directory
    *
diff --git a/app/src/test/java/app/passwordstore/data/repo/PasswordRepositoryTest.kt b/app/src/test/java/app/passwordstore/data/repo/PasswordRepositoryTest.kt
new file mode 100644
index 00000000..1ebe9840
--- /dev/null
+++ b/app/src/test/java/app/passwordstore/data/repo/PasswordRepositoryTest.kt
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+package app.passwordstore.data.repo
+
+import java.nio.file.Files
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class PasswordRepositoryTest {
+
+  @Test
+  fun rebasedBranchReadsTheBranchOfAStoppedRebase() {
+    val gitDir = Files.createTempDirectory("aps-git").toFile()
+    assertNull(PasswordRepository.rebasedBranch(gitDir))
+
+    val headName = gitDir.resolve("rebase-merge").apply { mkdirs() }.resolve("head-name")
+    headName.writeText("refs/heads/master\n")
+    assertEquals("master", PasswordRepository.rebasedBranch(gitDir))
+
+    // A rebase of a detached HEAD records "detached HEAD", which is not a branch.
+    headName.writeText("detached HEAD\n")
+    assertNull(PasswordRepository.rebasedBranch(gitDir))
+    gitDir.deleteRecursively()
+  }
+}