Check that the test affects env::temp_dir() as desired

This check is probably overzealous in that a path that identifies
the same directory in a different way that is non-equivalent under
path equality would also be acceptable. But a more restrictive
check is simpler, and since we have canonicalized the path and used
it after that for both changing the directory and setting the
environment variables we intend that `env::temp_dir()` will use,
that is unlikely to be a problem.

That it not to say that this cannot break in practice. Rather, it
can break, but if it does, there is a substantial likelihood that
the test is not ensuring the behavior it wishes to check. So to
preserve it as a regression test, failures of this new assertion
should be examined.

This commit also removes some old cruft (commented out test code I
had used while investigating a test bug) and rewords some custom
assertion messages so it is clearer what the expectation is.

gix-path/src/env/git/tests.rs

@@ -384,7 +384,7 @@ fn exe_info_never_from_local_scope() {
     let maybe_path = super::exe_info();
     assert!(
         maybe_path.is_none(),
-        "Finds no config path if the config would be local"
+        "Should find no config path if the config would be local"
     );
 }
 
@@ -403,13 +403,11 @@ fn exe_info_never_from_local_scope_even_if_temp_is_here() {
         .set("TMPDIR", repo_str) // Mainly for Unix.
         .set("TMP", repo_str) // Mainly for Windows.
         .set("TEMP", repo_str); // Mainly for Windows, too.
-    //assert_eq!(std::env::temp_dir(), repo);
-    //assert_eq!(std::env::temp_dir(), Path::new("/a/b/c"), "Bogus assertion to debug test");
-    //std::thread::sleep(std::time::Duration::from_secs(3600));
+    assert_eq!(std::env::temp_dir(), repo, "It is likely that setting up the test failed");
     let maybe_path = super::exe_info();
     assert!(
         maybe_path.is_none(),
-        "Finds no config path if the config would be local even in a `/tmp`-like dir"
+        "Should find no config path if the config would be local even in a `/tmp`-like dir"
     );
 }