Fix is_managed check for upgradable Python installs

Author: zanieb

crates/uv-python/src/interpreter.rs

@@ -292,11 +292,7 @@ impl Interpreter {
             return false;
         };
 
-        installations
-            .find_all()
-            .into_iter()
-            .flatten()
-            .any(|install| install.path() == self.sys_base_prefix)
+        self.sys_base_prefix.starts_with(installations.root())
     }
 
     /// Returns `Some` if the environment is externally managed, optionally including an error

crates/uv/tests/it/venv.rs

@@ -1348,6 +1348,7 @@ fn venv_python_preference() {
     ----- stderr -----
     Using CPython 3.11.[X] interpreter at: [PYTHON-3.11]
     Creating virtual environment at: .venv
+    warning: A virtual environment already exists at `.venv`. In the future, uv will require `--clear` to replace it
     Activate with: source .venv/[BIN]/activate
     ");
 
@@ -1359,6 +1360,7 @@ fn venv_python_preference() {
     ----- stderr -----
     Using CPython 3.11.[X] interpreter at: [PYTHON-3.11]
     Creating virtual environment at: .venv
+    warning: A virtual environment already exists at `.venv`. In the future, uv will require `--clear` to replace it
     Activate with: source .venv/[BIN]/activate
     ");
 
@@ -1370,6 +1372,7 @@ fn venv_python_preference() {
     ----- stderr -----
     Using CPython 3.12.[X] interpreter at: [PYTHON-3.12]
     Creating virtual environment at: .venv
+    warning: A virtual environment already exists at `.venv`. In the future, uv will require `--clear` to replace it
     Activate with: source .venv/[BIN]/activate
     ");
 
@@ -1381,6 +1384,7 @@ fn venv_python_preference() {
     ----- stderr -----
     Using CPython 3.12.[X] interpreter at: [PYTHON-3.12]
     Creating virtual environment at: .venv
+    warning: A virtual environment already exists at `.venv`. In the future, uv will require `--clear` to replace it
     Activate with: source .venv/[BIN]/activate
     ");
 }