fix(resolver): Don't do git fetches when updating workspace members

Before, when running `cargo update <member>`, we'd not reuse the
previous resolve result and when the resolver started walking into the
dependencies, it would do a git fetch.

Now, we won't even try to resolve the workspace members and so we won't
look at those dependencies and do git fetch.

This will make `cargo update <workspace-member>`
match `cargo update --workspace`.
I considered whether there were other ways of handling this but I
figured aiming for consistency in approaches was the best way.
We can investigate improving those approaches separately.

There are other discrepancies in the different code paths (handling of
patches, adding sources) but I'm deferring looking over those.

Between this and rust-lang#12602, this should finnally resolve rust-lang#12599.

Fixes rust-lang#12599

src/cargo/ops/cargo_generate_lockfile.rs

@@ -122,6 +122,26 @@ pub fn update_lockfile(ws: &Workspace<'_>, opts: &UpdateOptions<'_>) -> CargoRes
             }
         }
 
+        // Mirror `--workspace` and never avoid workspace members.
+        // Filtering them out here so the above processes them normally
+        // so their dependencies can be updated as requested
+        to_avoid = to_avoid
+            .into_iter()
+            .filter(|id| {
+                for package in ws.members() {
+                    let member_id = package.package_id();
+                    // Skip checking the `version` because `previous_resolve` might have a stale
+                    // value.
+                    // When dealing with workspace members, the other fields should be a
+                    // sufficiently unique match.
+                    if id.name() == member_id.name() && id.source_id() == member_id.source_id() {
+                        return false;
+                    }
+                }
+                true
+            })
+            .collect();
+
         registry.add_sources(sources)?;
     }
 

tests/testsuite/update.rs

@@ -1091,11 +1091,8 @@ rustdns.workspace = true
     p.cargo("update -p rootcrate")
         .with_stderr(&format!(
             "\
-[UPDATING] git repository `{}`
 [UPDATING] rootcrate v2.29.8 ([CWD]/rootcrate) -> v2.29.81
-[UPDATING] rustdns v0.5.0 ([..]) -> [..]
 [UPDATING] subcrate v2.29.8 ([CWD]/subcrate) -> v2.29.81",
-            git_project.url(),
         ))
         .run();
 }
@@ -1182,11 +1179,8 @@ rustdns.workspace = true
     p.cargo("update -p crate2")
         .with_stderr(&format!(
             "\
-[UPDATING] git repository `{}`
 [UPDATING] crate1 v2.29.8 ([CWD]/crate1) -> v2.29.81
-[UPDATING] crate2 v2.29.8 ([CWD]/crate2) -> v2.29.81
-[UPDATING] rustdns v0.5.0 ([..]) -> [..]",
-            git_project.url(),
+[UPDATING] crate2 v2.29.8 ([CWD]/crate2) -> v2.29.81",
         ))
         .run();
 }