Improved prompt speed when hg is not installed.
Prevented bash from walking the path looking for hg when it is not
installed during each prompt refresh.
diff --git a/themes/base.theme.bash b/themes/base.theme.bash
index 629e81d..44c34ab 100644
--- a/themes/base.theme.bash
+++ b/themes/base.theme.bash
@@ -34,7 +34,7 @@
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