Set color bash prompt according to active virtualenv, git branch and return status of last command.

bash_aliases.sh

txtblk='\e[0;30m' # Black - Regular
txtred='\e[0;31m' # Red
txtgrn='\e[0;32m' # Green
txtylw='\e[0;33m' # Yellow
txtblu='\e[0;34m' # Blue
txtpur='\e[0;35m' # Purple
txtcyn='\e[0;36m' # Cyan
txtwht='\e[0;37m' # White
 
bldblk='\e[1;30m' # Black - Bold
bldred='\e[1;31m' # Red
bldgrn='\e[1;32m' # Green
bldylw='\e[1;33m' # Yellow
bldblu='\e[1;34m' # Blue
bldpur='\e[1;35m' # Purple
bldcyn='\e[1;36m' # Cyan
bldwht='\e[1;37m' # White
 
undblk='\e[4;30m' # Black - Underline
undred='\e[4;31m' # Red
undgrn='\e[4;32m' # Green
undylw='\e[4;33m' # Yellow
undblu='\e[4;34m' # Blue
undpur='\e[4;35m' # Purple
undcyn='\e[4;36m' # Cyan
undwht='\e[4;37m' # White
 
bakblk='\e[40m'   # Black - Background
bakred='\e[41m'   # Red
badgrn='\e[42m'   # Green
bakylw='\e[43m'   # Yellow
bakblu='\e[44m'   # Blue
bakpur='\e[45m'   # Purple
bakcyn='\e[46m'   # Cyan
bakwht='\e[47m'   # White
 
txtrst='\e[0m'    # Text Reset


parse_git_branch() {
  git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/(\1)/'
}

# The various escape codes that we can use to color our prompt.
        RED="\[\033[0;31m\]"
     YELLOW="\[\033[1;33m\]"
      GREEN="\[\033[0;32m\]"
       BLUE="\[\033[1;34m\]"
  LIGHT_RED="\[\033[1;31m\]"
LIGHT_GREEN="\[\033[1;32m\]"
      WHITE="\[\033[1;37m\]"
 LIGHT_GRAY="\[\033[0;37m\]"
 COLOR_NONE="\[\e[0m\]"

# Detect whether the current directory is a git repository.
function is_git_repository {
  git branch > /dev/null 2>&1
}

# Determine the branch/state information for this git repository.
function set_git_branch {
  # Capture the output of the "git status" command.
  git_status="$(git status 2> /dev/null)"

  # Set color based on clean/staged/dirty.
  if [[ ${git_status} =~ "working directory clean" ]]; then
    state="${bldgrn}"
  elif [[ ${git_status} =~ "Changes to be committed" ]]; then
    state="${bldylw}"
  else
    state="${LIGHT_RED}"
  fi

  # Set arrow icon based on status against remote.
  remote_pattern="Your branch is (.*) (of|by|with)"
  if [[ ${git_status} =~ ${remote_pattern} ]]; then
#    echo "ofof = ${BASH_REMATCH[1]}"
    if [[ ${BASH_REMATCH[1]} == ahead* ]]; then
      remote="↑"
    elif [[ ${BASH_REMATCH[1]} == behind* ]]; then
      remote="↓"
    else
      remote="--"
    fi
  else
    remote=""
  fi

  diverge_pattern="Your branch and (.*) have diverged"
  if [[ ${git_status} =~ ${diverge_pattern} ]]; then
    remote="↕"
  fi

  # Get the name of the branch.
  branch_pattern="^(# )?On branch ([^${IFS}]*)"
  if [[ ${git_status} =~ ${branch_pattern} ]]; then
    branch=${BASH_REMATCH[2]}
  fi
  branch="$(git rev-parse --abbrev-ref HEAD)" # replace all 4 lines with this.

  # Set the final branch string.
#  echo "bran ${branch}"
  BRANCH="${state}(${branch})${remote}${COLOR_NONE} "
}

# Return the prompt symbol to use, colorized based on the return value of the
# previous command.
function set_prompt_symbol () {
  if test $1 -eq 0 ; then
      PROMPT_SYMBOL="${GREEN}<\$>${COLOR_NONE}"
  else
      PROMPT_SYMBOL="${LIGHT_RED}<\$>${COLOR_NONE}"
  fi
}

# Determine active Python virtualenv details.
function set_virtualenv () {
  if test -z "$VIRTUAL_ENV" ; then
      PYTHON_VIRTUALENV=""
  else
      PYTHON_VIRTUALENV="${BLUE}[`basename \"$VIRTUAL_ENV\"`]${COLOR_NONE} "
  fi
}

# Set the full bash prompt.
function set_bash_prompt () {
  # Set the PROMPT_SYMBOL variable. We do this first so we don't lose the
  # return value of the last command.
  set_prompt_symbol $?
  
  # Set the PYTHON_VIRTUALENV variable.
  set_virtualenv

      # Set the BRANCH variable.
	  if is_git_repository ; then
	#    echo "is git repo"
	    set_git_branch	 
	  else
	    BRANCH=''
	  fi
    
    SHOW_FACE="\`if [ \$? = 0 ]; then echo \[\e[33m\]^_^\[\e[0m\]; else echo \[\e[31m\]O_O\[\e[0m\]; fi\`"
    PS1="\n${PYTHON_VIRTUALENV}${GREEN}${txtred}\u@\h:${bldcyn}[\w]:${bldgrn}${BRANCH}\n${SHOW_FACE}..${PROMPT_SYMBOL} "
}

PROMPT_COMMAND=set_bash_prompt

^_^ works for me!