version-file: Fix infinite loop for relative paths

find_local_version_file reduces its target with ${root%/*}, but that leaves a slash-less relative argument such as "." unchanged, leading to an infinite loop

Signed-off-by: 付典 <fudianchn@gmail.com>

libexec/pyenv-version-file

@@ -8,6 +8,9 @@ target_dir="$1"
 
 find_local_version_file() {
   local root="$1"
+  # Nonexistent paths are UB as of this writing.
+  # Relative ones cause a failure but absolute ones don't
+  [[ $root != /* ]] && root=$(CDPATH= cd -- "$root" && pwd)
   while ! [[ "$root" =~ ^//[^/]*$ ]]; do
     if [ -f "${root}/.python-version" ]; then
       echo "${root}/.python-version"

test/version-file.bats

@@ -73,3 +73,15 @@ create_file() {
   run pyenv-version-file "$PWD"
   assert_failure ""
 }
+
+@test "walks up beyond cwd for a relative path" {
+  create_file ".python-version"
+  mkdir -p project/subdir
+  cd project
+  # Run with CPU-time limit because this used to loop forever
+  run bash -c 'ulimit -t 5; pyenv-version-file .'
+  assert_success "${PYENV_TEST_DIR}/.python-version"
+
+  run pyenv-version-file ./subdir
+  assert_success "${PYENV_TEST_DIR}/.python-version"
+}