cook: don't stage recipes with cargo path deps escaping their source

redbear-greeter's manifest has
  redbear-login-protocol = { path = "../../redbear-login-protocol/source" }
Cargo resolves that relative to the manifest, so out-of-tree staging pointed it
at <recipe>/target/redbear-login-protocol/source:
  failed to read .../target/redbear-login-protocol/source/Cargo.toml
  No such file or directory (os error 2)

Rewriting the manifest would silently change dependency paths behind the
recipe's back. Leaving these in tree is the honest option: they are cargo
recipes that do not sed their source, so the mutation risk staging exists to
prevent does not apply to them.

src/cook/cook_build.rs

@@ -1001,7 +1001,27 @@ pub fn build(
             // ones recipes actually rewrite.
             let source_is_submodule = source_real.join(".git").exists();
 
+            // Cargo path dependencies that ESCAPE the source tree cannot be
+            // staged: they are resolved relative to the manifest, so moving the
+            // manifest breaks them. redbear-greeter depends on
+            // `../redbear-login-protocol/source`, which under staging resolved
+            // to <recipe>/target/redbear-login-protocol/source and failed:
+            //   failed to read .../target/redbear-login-protocol/source/Cargo.toml
+            //   No such file or directory (os error 2)
+            // Rewriting the manifests would edit dependency paths behind the
+            // recipe's back; leaving these in tree is the honest option. They
+            // are Rust recipes that build via cargo and do not sed their source,
+            // so the mutation risk staging protects against does not apply.
+            let escapes_source_tree = fs::read_to_string(source_real.join("Cargo.toml"))
+                .map(|manifest| {
+                    manifest
+                        .lines()
+                        .any(|l| l.contains("path") && l.contains("\"..") )
+                })
+                .unwrap_or(false);
+
             let source_is_tracked = !source_is_submodule
+                && !escapes_source_tree
                 && std::env::var_os("REDBEAR_IN_TREE_BUILD").is_none()
                 && Command::new("git")
                     .arg("ls-files")