Prevented bash from walking the path looking for hg when it is not
installed during each prompt refresh.
if [[ -f .git/HEAD ]]; then SCM=$SCM_GIT
elif [[ -n "$(git symbolic-ref HEAD 2> /dev/null)" ]]; then SCM=$SCM_GIT
elif [[ -d .hg ]]; then SCM=$SCM_HG
- elif [[ -n "$(hg root 2> /dev/null)" ]]; then SCM=$SCM_HG
+ elif which hg &> /dev/null && [[ -n "$(hg root 2> /dev/null)" ]]; then SCM=$SCM_HG
elif [[ -d .svn ]]; then SCM=$SCM_SVN
else SCM=$SCM_NONE
fi