Find Ansible's interpreter also behind python-exec and wrapper scripts

On Gentoo, the shebang of `ansible-playbook` is the python-exec
dispatcher (`#!/usr/bin/python-exec2c`), which bin/ansible-python.sh
took for an interpreter, because its name starts with `python`.
python-exec only runs the programs it wraps, so every `just run…`
recipe failed with "no python-exec wrapped executable found".

Now only names like `python`, `python3` or `python3.14` are trusted.
For anything else (python-exec, wrapper scripts as on Nix), Ansible is
asked which interpreter it runs on (`ansible-playbook --version`),
before falling back to `python3`, which may lack PyYAML (e.g. in an
active virtualenv).

Same as https://github.com/mother-of-all-self-hosting/mash-playbook/commit/a685940a

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

bin/ansible-python.sh

@@ -11,12 +11,12 @@
 # where the system's `python3` may lack it.
 #
 # The interpreter is taken from the first line (shebang) of `ansible-playbook`.
-# If that is not a Python interpreter (e.g. `ansible-playbook` is a wrapper script), or Ansible is not installed,
-# `python3` is used.
+# If that is not a Python interpreter (e.g. `ansible-playbook` is a wrapper script, or Gentoo's python-exec),
+# Ansible is asked which interpreter it runs on. If that fails too, or Ansible is not installed, `python3` is used.
 
 set -eu
 
-python=python3
+interpreter=
 
 ansible_playbook_path=$(command -v ansible-playbook 2>/dev/null || true)
 if [ -n "$ansible_playbook_path" ] && [ -f "$ansible_playbook_path" ]; then
@@ -30,15 +30,26 @@ EOF
             if [ "$(basename "$interpreter")" = "env" ]; then
                 interpreter=${next_word:-}
             fi
-            case "$(basename "${interpreter:-none}")" in
-                python*)
-                    if command -v "$interpreter" >/dev/null 2>&1; then
-                        python=$interpreter
-                    fi
-                    ;;
-            esac
             ;;
     esac
+
+    # Only names like `python`, `python3` or `python3.14` are interpreters (`python-exec2c` is not)
+    case "$(basename "${interpreter:-none}")" in
+        python | python[0-9] | python[0-9].[0-9]*) ;;
+        *) interpreter= ;;
+    esac
+
+    if [ -z "$interpreter" ] || ! command -v "$interpreter" >/dev/null 2>&1; then
+        # The interpreter ends a line like: `  python version = 3.14.0 (main, …) [GCC …] (/usr/bin/python3.14)`
+        interpreter=$("$ansible_playbook_path" --version 2>/dev/null \
+            | sed -n 's/^ *python version = .*(\([^()]*\))$/\1/p' | head -n 1) || true
+    fi
+fi
+
+if [ -n "$interpreter" ] && command -v "$interpreter" >/dev/null 2>&1; then
+    python=$interpreter
+else
+    python=python3
 fi
 
 exec "$python" "$@"