fix(platform): a staging name is refused for a path separator only

crates/platform/src/staging.rs

@@ -44,7 +44,7 @@ fn create_staging_as(
     keep: Option<&std::fs::Metadata>,
 ) -> std::io::Result<(PathBuf, std::fs::File)> {
     // One name, in `dir`: a separator in it would put the staging file somewhere else.
-    if name.is_empty() || name.contains(['/', '\\']) || std::path::Path::new(name).components().count() != 1 {
+    if name.is_empty() || name.contains(['/', '\\']) {
         return Err(std::io::Error::new(std::io::ErrorKind::InvalidInput, "the file name is not a single name"));
     }
     // At most 128 bytes of the target's name, cut between characters, so the staging name fits

crates/platform/src/staging/tests.rs

@@ -464,7 +464,7 @@ fn a_replaced_link_keeps_its_own_attributes_not_its_targets() {
 #[test]
 fn a_name_with_path_components_is_refused() {
     let dir = test_dir("components");
-    for name in ["../out.pdf", "sub/out.pdf", "sub\\out.pdf", "/out.pdf", "", "."] {
+    for name in ["../out.pdf", "sub/out.pdf", "sub\\out.pdf", "/out.pdf", ""] {
         let err = create_staging(&dir, name, StagingName::SuffixThenTag, [0xab]).unwrap_err();
         assert_eq!(err.kind(), std::io::ErrorKind::InvalidInput, "{name:?}");
     }