[Fix] nvm_find_up, nvm_find_project_dir: stop at a Windows drive root instead of looping forever

With a Windows-style `$PWD` (e.g. `D:/Work`, as Git Bash inherits when launched
by a native Windows program), `${path_%/*}` stops changing at `D:`, so the walk
never ends and sourcing `nvm.sh` hangs. Stop when going up doesn't change the
path, which also covers the existing `.` case.

Fixes #3967.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RBGzjdkmgq6LSA7SFtjRsY

nvm.sh

@@ -815,9 +815,13 @@ nvm_tree_contains_path() {
 
 nvm_find_project_dir() {
   local path_
+  local parent_
   path_="${PWD}"
-  while [ "${path_}" != "" ] && [ "${path_}" != '.' ] && [ ! -f "${path_}/package.json" ] && [ ! -d "${path_}/node_modules" ]; do
-    path_=${path_%/*}
+  while [ "${path_}" != "" ] && [ ! -f "${path_}/package.json" ] && [ ! -d "${path_}/node_modules" ]; do
+    parent_=${path_%/*}
+    # stop when there is nowhere left to go up, e.g. `.` or a Windows drive root like `C:`
+    [ "${parent_}" != "${path_}" ] || break
+    path_="${parent_}"
   done
   nvm_echo "${path_}"
 }
@@ -825,9 +829,13 @@ nvm_find_project_dir() {
 # Traverse up in directory tree to find containing folder
 nvm_find_up() {
   local path_
+  local parent_
   path_="${PWD}"
-  while [ "${path_}" != "" ] && [ "${path_}" != '.' ] && [ ! -f "${path_}/${1-}" ]; do
-    path_=${path_%/*}
+  while [ "${path_}" != "" ] && [ ! -f "${path_}/${1-}" ]; do
+    parent_=${path_%/*}
+    # stop when there is nowhere left to go up, e.g. `.` or a Windows drive root like `C:`
+    [ "${parent_}" != "${path_}" ] || break
+    path_="${parent_}"
   done
   nvm_echo "${path_}"
 }

test/fast/Unit tests/nvm_find_project_dir

@@ -35,3 +35,6 @@ ACTUAL="$(PWD=$TEST_DIR/no-nesting-pkg nvm_find_project_dir)"
 
 ACTUAL="$(PWD="." nvm_find_project_dir)"
 [ "${ACTUAL}" = "." ] || die "insufficient permissions for pwd: got ${ACTUAL}"
+
+ACTUAL="$(PWD="Q:/nonexistent/dir" nvm_find_project_dir)"
+[ "${ACTUAL}" = "Q:" ] || die "Windows-style drive path from pwd: got ${ACTUAL}"

test/fast/Unit tests/nvm_find_up

@@ -23,5 +23,6 @@ TEST_DIR="$PWD"
 [ "~$(PWD=$TEST_DIR/tmp_nvm_find_up/a/b/c nvm_find_up 'test')" = "~$TEST_DIR/tmp_nvm_find_up/a/b/c" ] || die "failed to find in current dir"
 [ "~$(PWD=$TEST_DIR/tmp_nvm_find_up/a/b/c/d nvm_find_up 'test')" = "~$TEST_DIR/tmp_nvm_find_up/a/b/c" ] || die "failed to find 1 level up from current dir"
 [ "~$(PWD="." nvm_find_up 'test')" = "~." ] || die "failed to handle '.' output from pwd"
+[ "~$(PWD="Q:/nonexistent/dir" nvm_find_up 'test')" = "~Q:" ] || die "failed to handle Windows-style drive path from pwd"
 
 cleanup