[Fix] install script: Don’t attempt to `cd` twice.

Fixes #1137.

install.sh

@@ -69,7 +69,7 @@ install_nvm_from_git() {
   if [ -d "$INSTALL_DIR/.git" ]; then
     echo "=> nvm is already installed in $INSTALL_DIR, trying to update using git"
     printf "\r=> "
-    cd "$INSTALL_DIR" && (git fetch 2> /dev/null || {
+    cd "$INSTALL_DIR" && (command git fetch 2> /dev/null || {
       echo >&2 "Failed to update nvm, run 'git fetch' in $INSTALL_DIR yourself." && exit 1
     })
   else
@@ -77,9 +77,11 @@ install_nvm_from_git() {
     echo "=> Downloading nvm from git to '$INSTALL_DIR'"
     printf "\r=> "
     mkdir -p "$INSTALL_DIR"
-    git clone "$(nvm_source)" "$INSTALL_DIR"
+    command git clone "$(nvm_source)" "$INSTALL_DIR" \
+      || echo >&2 "Failed to clone nvm repo. Please report this!" && exit 1
+    cd "$INSTALL_DIR"
   fi
-  cd "$INSTALL_DIR" && command git checkout --quiet "$(nvm_latest_version)"
+  command git checkout --quiet "$(nvm_latest_version)"
   if [ ! -z "$(cd "$INSTALL_DIR" && git show-ref refs/heads/master)" ]; then
     if git branch --quiet 2>/dev/null; then
       cd "$INSTALL_DIR" && command git branch --quiet -D master >/dev/null 2>&1