git-prompt.sh: Don't error on null ${ZSH,BASH}_VERSION, $short_sha

When the shell is in "nounset" or "set -u" mode, referencing unset or
null variables results in an error. Protect $ZSH_VERSION and
$BASH_VERSION against that, and initialize $short_sha before use.

Signed-off-by: Ville Skyttä <ville.skytta@iki.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 366f0bc1e9b5597f1714574700452cd241c14f8d..ba599fc4a1bc9210bbf73ae2ff3ed0edb2a96c36 100644 (file)
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -355,8 +355,8 @@ __git_ps1 ()
        # incorrect.)
        #
        local ps1_expanded=yes
-       [ -z "$ZSH_VERSION" ] || [[ -o PROMPT_SUBST ]] || ps1_expanded=no
-       [ -z "$BASH_VERSION" ] || shopt -q promptvars || ps1_expanded=no
+       [ -z "${ZSH_VERSION-}" ] || [[ -o PROMPT_SUBST ]] || ps1_expanded=no
+       [ -z "${BASH_VERSION-}" ] || shopt -q promptvars || ps1_expanded=no
 
        local repo_info rev_parse_exit_code
        repo_info="$(git rev-parse --git-dir --is-inside-git-dir \
@@ -368,7 +368,7 @@ __git_ps1 ()
                return $exit
        fi
 
-       local short_sha
+       local short_sha=""
        if [ "$rev_parse_exit_code" = "0" ]; then
                short_sha="${repo_info##*$'\n'}"
                repo_info="${repo_info%$'\n'*}"