Omit PEP 751 version for source trees (#13030)

## Summary

This is a "MUST NOT" in the spec.

crates/uv-resolver/src/lock/export/pylock_toml.rs

@@ -289,10 +289,15 @@ impl<'lock> PylockToml {
                 continue;
             }
 
+            // "The version MUST NOT be included when it cannot be guaranteed to be consistent with the code used (i.e. when a source tree is used)."
+            let version = version
+                .as_ref()
+                .filter(|_| !matches!(&**dist, Dist::Source(SourceDist::Directory(..))));
+
             // Create a `pylock.toml`-style package.
             let mut package = PylockTomlPackage {
                 name: dist.name().clone(),
-                version: version.clone(),
+                version: version.cloned(),
                 marker: node.marker.pep508(),
                 requires_python: None,
                 dependencies: vec![],
@@ -737,9 +742,21 @@ impl<'lock> PylockToml {
                 .index(target.install_path())?
                 .map(IndexUrl::into_url);
 
+            // Extract the `packages.name` field.
+            let name = package.id.name.clone();
+
+            // Extract the `packages.version` field.
+            // "The version MUST NOT be included when it cannot be guaranteed to be consistent with the code used (i.e. when a source tree is used)."
+            let version = package
+                .id
+                .version
+                .as_ref()
+                .filter(|_| directory.is_none())
+                .cloned();
+
             let package = PylockTomlPackage {
-                name: package.id.name.clone(),
+                name,
-                version: package.id.version.clone(),
+                version,
                 marker: node.marker,
                 requires_python: None,
                 dependencies: vec![],

crates/uv/tests/it/export.rs

@@ -3281,7 +3281,6 @@ fn pep_751_dependency() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3343,7 +3342,6 @@ fn pep_751_export_no_header() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3454,7 +3452,6 @@ fn pep_751_dependency_extra() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3515,7 +3512,6 @@ fn pep_751_project_extra() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3555,7 +3551,6 @@ fn pep_751_project_extra() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3595,7 +3590,6 @@ fn pep_751_project_extra() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3642,7 +3636,6 @@ fn pep_751_project_extra() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3689,7 +3682,6 @@ fn pep_751_project_extra() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -3995,7 +3987,6 @@ fn pep_751_infer_output_format() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]
@@ -4035,7 +4026,6 @@ fn pep_751_infer_output_format() -> Result<()> {
 
     [[packages]]
     name = "project"
-    version = "0.1.0"
     directory = { path = ".", editable = true }
 
     [[packages]]

crates/uv/tests/it/pip_compile.rs

@@ -16420,7 +16420,6 @@ fn pep_751_compile_directory() -> Result<()> {
 
     [[packages]]
     name = "foo"
-    version = "1.0.0"
     directory = { path = "foo" }
 
     [[packages]]