fix(git-lib): avoid regex error with non-ASCII branch names

_omz_git_prompt_status was emitting "regex matching error: illegal byte
sequence" when the git branch name contained non-ASCII characters (e.g.
Chinese). The zsh =~ operator uses locale-aware POSIX ERE, so character
classes like [^ ]+ reject multibyte sequences unless LC_ALL=C is set.
Fix by setting LC_ALL=C around all regex operations in the function and
restoring it afterwards.

Fixes #13330

lib/git.zsh

@@ -103,6 +103,11 @@ function _omz_git_prompt_status() {
   local status_lines
   status_lines=("${(@f)${status_text}}")
 
+  # Use C locale for regex matching to avoid "illegal byte sequence" errors
+  # when branch names or file paths contain non-ASCII characters (e.g. Chinese)
+  local _omz_lc_all=$LC_ALL
+  LC_ALL=C
+
   # If the tracking line exists, get and parse it
   if [[ "$status_lines[1]" =~ "^## [^ ]+ \[(.*)\]" ]]; then
     local branch_statuses
@@ -126,6 +131,8 @@ function _omz_git_prompt_status() {
     fi
   done
 
+  LC_ALL=$_omz_lc_all
+
   # Display the seen statuses in the order specified
   local status_prompt
   for status_constant in $status_constants; do

lib/tests/git.test.zsh

@@ -0,0 +1,74 @@
+#!/usr/bin/zsh -df
+
+# Regression tests for lib/git.zsh
+
+local -i _failures=0
+
+run_test() {
+  local description="$1"
+  local got="$2"
+  local expected="$3"
+
+  print -u2 "Test: $description"
+  if [[ "$got" == "$expected" ]]; then
+    print -u2 "\e[32mSuccess\e[0m"
+  else
+    print -u2 "\e[31mError\e[0m"
+    print -u2 "  expected: ${(q)expected}"
+    print -u2 "  got:      ${(q)got}"
+    (( _failures++ ))
+  fi
+  print -u2 ""
+}
+
+# ---------------------------------------------------------------------------
+# Set up: source git.zsh and override __git_prompt_git with a controllable mock
+# ---------------------------------------------------------------------------
+
+source "${0:h:h}/git.zsh" 2>/dev/null
+
+# The mock returns canned `git status --porcelain -b` output and denies stash.
+# Callers set _mock_status_output before calling _omz_git_prompt_status.
+_mock_status_output=""
+function __git_prompt_git() {
+  case "$*" in
+    "config --get oh-my-zsh.hide-status") return 1 ;;
+    "rev-parse --verify refs/stash")       return 1 ;;
+    "status --porcelain -b")               printf "%s\n" "$_mock_status_output" ;;
+    *)                                     return 1 ;;
+  esac
+}
+
+# ---------------------------------------------------------------------------
+# Bug #13330: _omz_git_prompt_status emits "regex matching error: illegal byte
+# sequence" when the git branch name contains non-ASCII characters (e.g. Chinese).
+# Root cause: zsh's =~ operator with [^ ]+ is locale-aware and rejects multibyte
+# sequences unless LC_ALL=C is set for the match.
+# ---------------------------------------------------------------------------
+
+# Chinese branch with upstream tracking info
+_mock_status_output="## 中文-1.0.0-中文...origin/中文-1.0.0-中文 [ahead 1]"
+stderr_output=$( { _omz_git_prompt_status } 2>&1 1>/dev/null )
+run_test \
+  "no 'illegal byte sequence' error with Chinese branch name (bug #13330)" \
+  "${stderr_output}" \
+  ""
+
+# Chinese branch with no tracking info (the regex should simply not match)
+_mock_status_output="## 中文-branch"
+stderr_output=$( { _omz_git_prompt_status } 2>&1 1>/dev/null )
+run_test \
+  "no error when Chinese branch has no tracking info" \
+  "${stderr_output}" \
+  ""
+
+# Regression: ASCII branch names must still be parsed correctly
+_mock_status_output="## main...origin/main [behind 3]"
+ZSH_THEME_GIT_PROMPT_BEHIND="<"
+output=$( _omz_git_prompt_status 2>/dev/null )
+run_test \
+  "ASCII branch with 'behind' tracking info still detected" \
+  "${output}" \
+  "<"
+
+exit $_failures