Don't autodelete directory after deleting the last file in it

Executing `git rm` on the last file in a directory makes Git remove not
only this file, but its parent directory as well.

Although it is Git's behavior, it is not convenient, and it is also
unexpected since `git rm` is not explicitly triggered by user who
deletes a file from the Project View.

GitVFSListener is triggered _after_ actual deletion of the file,
so the only thing Git should do is to delete the file from the index:
git rm --cached. This does the same as `git rm`, but prevents Git from
removing the directory (since files are not touched on disk, only
in the index).

Fixes IDEA-75590

plugins/git4idea/src/git4idea/vfs/GitVFSListener.java

@@ -180,7 +180,7 @@ public class GitVFSListener extends VcsVFSListener {
       HashSet<File> filesToRefresh = new HashSet<>();
 
       public void execute(@NotNull VirtualFile root, @NotNull List<FilePath> files) throws VcsException {
-        GitFileUtils.delete(myProject, root, files, "--ignore-unmatch");
+        GitFileUtils.delete(myProject, root, files, "--ignore-unmatch", "--cached");
         if (!myProject.isDisposed()) {
           VcsFileUtil.markFilesDirty(myProject, files);
         }

plugins/git4idea/tests/git4idea/checkin/GitRmTest.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2000-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package git4idea.checkin
+
+import com.intellij.openapi.application.runWriteAction
+import com.intellij.openapi.command.CommandProcessor
+import com.intellij.openapi.vcs.FileStatus
+import com.intellij.openapi.vcs.VcsVFSListener
+import com.intellij.openapi.vfs.LocalFileSystem
+import com.intellij.testFramework.runInEdtAndWait
+import com.intellij.vcsUtil.VcsUtil.getFilePath
+import git4idea.test.GitSingleRepoTest
+import git4idea.test.git
+import java.io.File
+
+class GitRmTest : GitSingleRepoTest() {
+
+  override fun getDebugLogCategories() = super.getDebugLogCategories().plus("#" + VcsVFSListener::class.java.name)
+
+  // IDEA-75590
+  fun `test empty directories are not removed on git rm`() {
+    val nestedDir = File(myProjectPath, "lib/subdir")
+    assertTrue("Directory $nestedDir wasn't created", nestedDir.mkdirs())
+    val file = File(nestedDir, "f.txt")
+    assertTrue("File $file wasn't created", file.createNewFile())
+    git("add .")
+    git("commit -m 'added file'")
+    val vf = LocalFileSystem.getInstance().refreshAndFindFileByIoFile(file)
+    assertNotNull("VirtualFile not found for file $file", vf)
+    vf!!
+
+    runInEdtAndWait {
+      CommandProcessor.getInstance().executeCommand(myProject, {
+        runWriteAction {
+          vf.delete(this)
+        }
+      }, null, null)
+    }
+    updateChangeListManager()
+
+    assertFalse("File wasn't deleted", file.exists())
+    assertTrue("Directory shouldn't have been deleted", nestedDir.exists())
+    val change = changeListManager.getChange(getFilePath(vf))
+    assertNotNull(change)
+    assertEquals(FileStatus.DELETED, change!!.fileStatus)
+  }
+}