Keep the window responsive and ssh connections safe

Commands that run git now run away from the thread that draws the
window, so a slow server no longer freezes it. ssh now notices a server
that stopped answering in about 10 seconds. The sockets for shared
connections go in the runtime folder, or else in a private gites folder
in the cache folder, never in /tmp; without either, connections are not
shared. A path that is exactly ~ now means the home folder on the
server.

Tests cover commit details through ssh, the message for a failed
connection, and a ~/ path end to end. The stand-in ssh is now set per
test, so a test can give it its own home folder.

src-tauri/src/details.rs

@@ -16,7 +16,7 @@ pub struct ChangedFile {
     pub deleted: Option<u32>,
 }
 
-#[derive(Serialize, Debug)]
+#[derive(Serialize, Debug, PartialEq)]
 pub struct CommitDetails {
     hash: String,
     author: String,
@@ -153,4 +153,37 @@ mod tests {
     fn parses_an_empty_diff() {
         assert_eq!(parse_files("", ""), vec![]);
     }
+
+    #[test]
+    fn shows_the_same_details_through_ssh() {
+        use std::process::Command;
+        let dir = std::env::temp_dir().join(format!("gites-details-ssh-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        let run = |args: &[&str]| {
+            let out = Command::new("git")
+                .arg("-C")
+                .arg(&dir)
+                .args(["-c", "user.name=Test", "-c", "user.email=test@example.com", "-c", "commit.gpgsign=false"])
+                .args(args)
+                .output()
+                .unwrap();
+            assert!(out.status.success(), "git {args:?}: {}", String::from_utf8_lossy(&out.stderr));
+            String::from_utf8_lossy(&out.stdout).trim().to_string()
+        };
+        run(&["init", "-q", "-b", "main"]);
+        std::fs::write(dir.join("it's $a; b.txt"), "one\ntwo\n").unwrap();
+        run(&["add", "-A"]);
+        run(&["commit", "-q", "-m", "first"]);
+        std::fs::write(dir.join("it's $a; b.txt"), "one\nthree\n").unwrap();
+        run(&["commit", "-q", "-am", "second\n\nwith a body"]);
+        let hash = run(&["rev-parse", "HEAD"]);
+        crate::test_ssh::fake_ssh();
+        let remote = Location::Ssh { target: "myserver".into(), path: dir.to_string_lossy().into_owned() };
+        let local = load(&Location::Local(dir.clone()), &hash).unwrap();
+        let through_ssh = load(&remote, &hash).unwrap();
+        assert_eq!(local.files, vec![file("M", "it's $a; b.txt", None, Some(1), Some(1))]);
+        assert_eq!(local, through_ssh);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
 }