Skip GitHub fast path when full commit is already known (#10800)

## Summary

If we have a `GitReference::FullCommit`, we don't need to go to GitHub
to resolve the SHA. We already have it!

crates/uv-git/src/git.rs

@@ -74,11 +74,7 @@ impl GitReference {
         if rev.starts_with("refs/") {
             Self::NamedRef(rev)
         } else if looks_like_commit_hash(&rev) {
-            if rev.len() == 40 {
-                Self::FullCommit(rev)
-            } else {
-                Self::BranchOrTagOrCommit(rev)
-            }
+            Self::BranchOrTagOrCommit(rev)
         } else {
             Self::BranchOrTag(rev)
         }
@@ -729,7 +725,7 @@ fn github_fast_path(
         GitReference::BranchOrTag(branch_or_tag) => branch_or_tag,
         GitReference::DefaultBranch => "HEAD",
         GitReference::NamedRef(rev) => rev,
-        GitReference::FullCommit(rev) | GitReference::BranchOrTagOrCommit(rev) => {
+        GitReference::BranchOrTagOrCommit(rev) => {
             // `revparse_single` (used by `resolve`) is the only way to turn
             // short hash -> long hash, but it also parses other things,
             // like branch and tag names, which might coincidentally be
@@ -754,12 +750,21 @@ fn github_fast_path(
             }
             rev
         }
-    };
+        GitReference::FullCommit(rev) => {
+            debug!("Skipping GitHub fast path; full commit hash provided: {rev}");
 
-    // TODO(charlie): If we _know_ that we have a full commit SHA, there's no need to perform this
-    // request. We can just return `FastPathRev::NeedsFetch`. However, we need to audit all uses of
-    // `GitReference::FullCommit` to ensure that we _know_ it's a SHA, as opposed to (e.g.) a Git
-    // tag that just "looks like" a commit (i.e., a tag composed of 40 hex characters).
+            let rev = GitOid::from_str(rev)?;
+            if let Some(ref local_object) = local_object {
+                if rev == *local_object {
+                    return Ok(FastPathRev::UpToDate);
+                }
+            }
+
+            // If we know the reference is a full commit hash, we can just return it without
+            // querying GitHub.
+            return Ok(FastPathRev::NeedsFetch(rev));
+        }
+    };
 
     let url = format!("https://api.github.com/repos/{owner}/{repo}/commits/{github_branch_name}");
 

crates/uv/tests/it/branching_urls.rs

@@ -667,7 +667,7 @@ fn branching_urls_of_different_sources_disjoint() -> Result<()> {
     [package.metadata]
     requires-dist = [
         { name = "iniconfig", marker = "python_full_version < '3.12'", url = "https://files.pythonhosted.org/packages/9b/dd/b3c12c6d707058fa947864b67f0c4e0c39ef8610988d7baea9578f3c48f3/iniconfig-1.1.1-py2.py3-none-any.whl" },
-        { name = "iniconfig", marker = "python_full_version >= '3.12'", git = "https://github.com/pytest-dev/iniconfig?rev=93f5930e668c0d1ddf4597e38dd0dea4e2665e7a#93f5930e668c0d1ddf4597e38dd0dea4e2665e7a" },
+        { name = "iniconfig", marker = "python_full_version >= '3.12'", git = "https://github.com/pytest-dev/iniconfig?rev=93f5930e668c0d1ddf4597e38dd0dea4e2665e7a" },
     ]
 
     [[package]]

crates/uv/tests/it/lock.rs

@@ -582,7 +582,7 @@ fn lock_sdist_git_subdirectory() -> Result<()> {
         ]
 
         [package.metadata]
-        requires-dist = [{ name = "example-pkg-a", git = "https://github.com/pypa/sample-namespace-packages.git?subdirectory=pkg_resources%2Fpkg_a&rev=df7530eeb8fa0cb7dbb8ecb28363e8e36bfa2f45#df7530eeb8fa0cb7dbb8ecb28363e8e36bfa2f45" }]
+        requires-dist = [{ name = "example-pkg-a", git = "https://github.com/pypa/sample-namespace-packages.git?subdirectory=pkg_resources%2Fpkg_a&rev=df7530eeb8fa0cb7dbb8ecb28363e8e36bfa2f45" }]
         "###
         );
     });
@@ -742,7 +742,7 @@ fn lock_sdist_git_pep508() -> Result<()> {
         ]
 
         [package.metadata]
-        requires-dist = [{ name = "uv-public-pypackage", git = "https://github.com/astral-test/uv-public-pypackage.git?rev=0dacfd662c64cb4ceb16e6cf65a157a8b715b979#0dacfd662c64cb4ceb16e6cf65a157a8b715b979" }]
+        requires-dist = [{ name = "uv-public-pypackage", git = "https://github.com/astral-test/uv-public-pypackage.git?rev=0dacfd662c64cb4ceb16e6cf65a157a8b715b979" }]
 
         [[package]]
         name = "uv-public-pypackage"
@@ -799,7 +799,7 @@ fn lock_sdist_git_pep508() -> Result<()> {
         ]
 
         [package.metadata]
-        requires-dist = [{ name = "uv-public-pypackage", git = "https://github.com/astral-test/uv-public-pypackage.git?rev=b270df1a2fb5d012294e9aaf05e7e0bab1e6a389#b270df1a2fb5d012294e9aaf05e7e0bab1e6a389" }]
+        requires-dist = [{ name = "uv-public-pypackage", git = "https://github.com/astral-test/uv-public-pypackage.git?rev=b270df1a2fb5d012294e9aaf05e7e0bab1e6a389" }]
 
         [[package]]
         name = "uv-public-pypackage"

crates/uv/tests/it/pip_install.rs

@@ -1725,7 +1725,7 @@ fn install_git_public_https_missing_commit() {
 
     let mut filters = context.filters();
     // Windows does not style the command the same as Unix, so we must omit it from the snapshot
-    filters.push(("`.*/git(.exe)? fetch .*`", "`git fetch [...]`"));
+    filters.push(("`.*/git(.exe)? rev-parse .*`", "`git rev-parse [...]`"));
     filters.push(("exit status", "exit code"));
 
     // There are flakes on Windows where this irrelevant error is appended
@@ -1745,11 +1745,15 @@ fn install_git_public_https_missing_commit() {
     ----- stderr -----
       × Failed to download and build `uv-public-pypackage @ git+https://github.com/astral-test/uv-public-pypackage@79a935a7a1a0ad6d0bdf72dce0e16cb0a24a1b3b`
       ├─▶ Git operation failed
-      ├─▶ failed to clone into: [CACHE_DIR]/git-v0/db/8dab139913c4b566
-      ├─▶ failed to fetch commit `79a935a7a1a0ad6d0bdf72dce0e16cb0a24a1b3b`
-      ╰─▶ process didn't exit successfully: `git fetch [...]` (exit code: 128)
+      ├─▶ failed to find branch, tag, or commit `79a935a7a1a0ad6d0bdf72dce0e16cb0a24a1b3b`
+      ╰─▶ process didn't exit successfully: `git rev-parse [...]` (exit code: 128)
+          --- stdout
+          79a935a7a1a0ad6d0bdf72dce0e16cb0a24a1b3b^0
+
           --- stderr
-          fatal: remote error: upload-pack: not our ref 79a935a7a1a0ad6d0bdf72dce0e16cb0a24a1b3b
+          fatal: ambiguous argument '79a935a7a1a0ad6d0bdf72dce0e16cb0a24a1b3b^0': unknown revision or path not in the working tree.
+          Use '--' to separate paths from revisions, like this:
+          'git <command> [<revision>...] -- [<file>...]'
     "###);
 }