Skip generating activate.csh for relocatable virtualenvs (#17759)

Closes https://github.com/astral-sh/uv/issues/17368

Co-authored-by: Claude <noreply@anthropic.com>

crates/uv-virtualenv/src/virtualenv.rs

@@ -447,6 +447,13 @@ pub(crate) fn create(
 
     // Add all the activate scripts for different shells
     for (name, template) in ACTIVATE_TEMPLATES {
+        // csh has no way to determine its own script location, so a relocatable
+        // activate.csh is not possible. Skip it entirely instead of generating a
+        // non-functional script.
+        if relocatable && *name == "activate.csh" {
+            continue;
+        }
+
         let path_sep = if cfg!(windows) { ";" } else { ":" };
 
         let relative_site_packages = [
@@ -477,9 +484,7 @@ pub(crate) fn create(
                     escape_posix_for_single_quotes(location.simplified().to_str().unwrap())
                 )
             }
-            // Note:
-            // * relocatable activate scripts appear not to be possible in csh.
-            // * `activate.ps1` is already relocatable by default.
+            // Note: `activate.ps1` is already relocatable by default.
             _ => escape_posix_for_single_quotes(location.simplified().to_str().unwrap()),
         };
 

crates/uv/tests/it/venv.rs

@@ -1302,6 +1302,11 @@ fn verify_pyvenv_cfg_relocatable() {
     activate_nu.assert(predicates::str::contains(
         r"let virtual_env = (path self | path dirname | path dirname)",
     ));
+
+    // csh cannot determine its own script location, so activate.csh should not
+    // be generated when --relocatable is used.
+    let activate_csh = scripts.child("activate.csh");
+    activate_csh.assert(predicates::path::missing());
 }
 
 /// With `relocatable-envs-default` preview feature, venvs are relocatable by default.