[vte] vte.sh: Append to PROMPT_COMMAND rather than overwriting it

[Egmont Koblinger <egmontkob src gnome org>]

commit 1e6e46f90a035a51b37576d059d6108ece1b4eaa
Author: Egmont Koblinger <egmont gmail com>
Date:   Sun Jan 18 18:17:07 2015 +0100

    vte.sh: Append to PROMPT_COMMAND rather than overwriting it
    
    https://bugzilla.gnome.org/show_bug.cgi?id=704960

 src/vte.sh |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/vte.sh b/src/vte.sh
index f6d2b12..4feabd1 100644
--- a/src/vte.sh
+++ b/src/vte.sh
@@ -57,7 +57,7 @@ __vte_prompt_command() {
 
 case "$TERM" in
   xterm*|vte*)
-    [ -n "$BASH_VERSION" ] && PROMPT_COMMAND="__vte_prompt_command" 
+    [ -n "$BASH_VERSION" ] && PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND; }__vte_prompt_command"
     [ -n "$ZSH_VERSION"  ] && precmd_functions+=(__vte_prompt_command)
     ;;
 esac