Various fixups:

- Use u32 for correct parameter formatting in pageserver mgmt API
  client
- Use a correctly formatted PgVersionId (not: PgMajorVersion) in
  test_branching.py
- Add some documentation on postgres_versioninfo::PgVersionId

libs/postgres_versioninfo/src/lib.rs

@@ -15,6 +15,7 @@ pub enum PgMajorVersion {
     // !!! When you add a new PgMajorVersion, don't forget to update PgMajorVersion::ALL
 }
 
+/// A full PostgreSQL version ID, in MMmmbb numerical format (Major/minor/bugfix)
 #[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq)]
 #[repr(transparent)]
 pub struct PgVersionId(u32);

libs/safekeeper_api/src/models.rs

@@ -24,7 +24,6 @@ pub struct TimelineCreateRequest {
     pub tenant_id: TenantId,
     pub timeline_id: TimelineId,
     pub mconf: Configuration,
-    /// In the PG_VERSION_NUM macro format, like 140017.
     pub pg_version: PgVersionId,
     pub system_id: Option<u64>,
     // By default WAL_SEGMENT_SIZE

pageserver/client/src/mgmt_api.rs

@@ -749,6 +749,8 @@ impl Client {
         pg_version: PgMajorVersion,
         basebackup_tarball: ReqwestBody,
     ) -> Result<()> {
+        let pg_version = pg_version.major_version_num();
+
         let uri = format!(
             "{}/v1/tenant/{tenant_id}/timeline/{timeline_id}/import_basebackup?base_lsn={base_lsn}&end_lsn={end_lsn}&pg_version={pg_version}",
             self.mgmt_api_endpoint,

test_runner/regress/test_branching.py

@@ -172,7 +172,7 @@ def test_cannot_create_endpoint_on_non_uploaded_timeline(neon_env_builder: NeonE
             env.initial_tenant,
             env.initial_timeline,
             MembershipConfiguration(generation=1, members=[sk.safekeeper_id()], new_members=None),
-            int(env.pg_version),
+            int(env.pg_version) * 10000,
             Lsn(0),
             None,
         )