`install.sh`: Don't give detached HEAD advice when installing

install.sh

@@ -110,13 +110,13 @@ install_nvm_from_git() {
         exit 2
       }
     else
-      command git clone "$(nvm_source)" -b "$(nvm_latest_version)" --depth=1 "${INSTALL_DIR}" || {
+      command git -c advice.detachedHead=false clone "$(nvm_source)" -b "$(nvm_latest_version)" --depth=1 "${INSTALL_DIR}" || {
         echo >&2 'Failed to clone nvm repo. Please report this!'
         exit 2
       }
     fi
   fi
-  command git --git-dir="$INSTALL_DIR"/.git --work-tree="$INSTALL_DIR" checkout -f --quiet "$(nvm_latest_version)"
+  command git -c advice.detachedHead=false --git-dir="$INSTALL_DIR"/.git --work-tree="$INSTALL_DIR" checkout -f --quiet "$(nvm_latest_version)"
   if [ ! -z "$(command git --git-dir="$INSTALL_DIR"/.git --work-tree="$INSTALL_DIR" show-ref refs/heads/master)" ]; then
     if command git --git-dir="$INSTALL_DIR"/.git --work-tree="$INSTALL_DIR" branch --quiet 2>/dev/null; then
       command git --git-dir="$INSTALL_DIR"/.git --work-tree="$INSTALL_DIR" branch --quiet -D master >/dev/null 2>&1