Fix multi-selection of files with common prefix not working in commit files panel

Equivalent to the change that was made to isDescendentOfSelectedNodes in
files_controller.go in a5eec48b4b.

pkg/gui/controllers/commits_files_controller.go

@@ -645,9 +645,13 @@ func isDescendentOfSelectedCommitFileNodes(node *filetree.CommitFileNode, select
 	nodePath := node.GetInternalPath()
 
 	for _, selectedNode := range selectedNodes {
+		if selectedNode.IsFile() {
+			continue
+		}
+
 		selectedNodePath := selectedNode.GetInternalPath()
 
-		if strings.HasPrefix(nodePath, selectedNodePath) && nodePath != selectedNodePath {
+		if strings.HasPrefix(nodePath, selectedNodePath+"/") {
 			return true
 		}
 	}

pkg/gui/controllers/files_controller.go

@@ -1552,6 +1552,8 @@ func normalisedSelectedNodes(selectedNodes []*filetree.FileNode) []*filetree.Fil
 	})
 }
 
+// NOTE: there's a duplicate of this function in commits_files_controller.go; if you make
+// changes here, make them there, too. (We should unify them using generics.)
 func isDescendentOfSelectedNodes(node *filetree.FileNode, selectedNodes []*filetree.FileNode) bool {
 	nodePath := node.GetInternalPath()
 

pkg/integration/tests/patch_building/select_direcories_sharing_prefix.go

@@ -41,19 +41,13 @@ var SelectDirecoriesSharingPrefix = NewIntegrationTest(NewIntegrationTestArgs{
 				Equals("  ▼ foo").IsSelected(),
 				Equals("    ● file").IsSelected(),
 				Equals("  ▼ foobar").IsSelected(),
-				/* EXPECTED:
 				Equals("    ● file"),
-				ACTUAL: */
-				Equals("    A file"),
 			)
 
 		t.Views().Information().Content(Contains("Building patch"))
 
 		t.Views().Secondary().Content(
-			/* EXPECTED:
 			Contains("foo/file").Contains("foobar/file"),
-			ACTUAL: */
-			Contains("foo/file").DoesNotContain("foobar/file"),
 		)
 	},
 })