This is my terminal log from that weird problem I had with Vagrant.

terminal-log

Last login: Mon Dec 19 23:03:45 on ttys000
✔ ~ 
23:04 $ pwd
/Users/XXXXXXXX
✔ ~ 
23:04 $ ls
Applications		Library			VirtualBox VMs
Creative Cloud Files	Movies			bin
Desktop			Music			vagrant-local
Documents		Pictures		wpcs
Downloads		Public
✔ ~ 
23:04 $ cd vagrant-local/
✔ ~/vagrant-local [develop ↓·32↑·1|✚ 1…2] 
23:04 $ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Checking if box 'ubuntu/trusty64' is up to date...
==> default: A newer version of the box 'ubuntu/trusty64' is available! You currently
==> default: have version '20161207.0.0'. The latest is version '20161214.0.0'. Run
==> default: `vagrant box update` to update.
==> default: [vagrant-hostsupdater] Checking for host entries
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 vvv
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 idi-insulation.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 mmt.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 pierresecondtest.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 pierrestestproject.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 pierrethirdtest.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 productivity.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 local.wordpress.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 src.wordpress-develop.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 build.wordpress-develop.dev
==> default: [vagrant-hostsupdater]   found entry for: 192.168.50.4 vvv.dev
==> default: Machine already provisioned. Run `vagrant provision` or use the `--provision`
==> default: flag to force provisioning. Provisioners marked to run always will still run.
==> default: Running provisioner: shell...
    default: Running: inline script
==> default: mysql stop/waiting
==> default: mysql start/running, process 8547
==> default: Running provisioner: shell...
    default: Running: inline script
==> default:  * Restarting nginx nginx
==> default: nginx: [emerg] directive "set" is not terminated by ";" in /etc/nginx/custom-sites/vvv-auto-wordpress-default-provisioner-837fb619e2bfc47058adcbbca596747e.conf:17
==> default: nginx: configuration file /etc/nginx/nginx.conf test failed
The SSH command responded with a non-zero exit status. Vagrant
assumes that this means the command failed. The output for this command
should be in the log above. Please read the output to determine what
went wrong.
✘-1 ~/vagrant-local [develop ↓·32↑·1|✚ 1…2] 
23:04 $ 

Also getting the same error.
It seems to point to the file /vagrant-local/www/wordpress-develop-provisioner/vvv-nginx.conf
However, line 15 in the file does end with ";"

`################################################################

WordPress stable nginx configuration

http://local.wordpress.dev - this server configuration is

setup to listen on port 80 for any requests coming in to

local.wordpress.dev and use the /srv/www/wordpress-default directory

to serve them.

server {
listen 80;
listen 443 ssl;
server_name local.wordpress.dev *.local.wordpress.dev ~^local.wordpress.\d+.\d+.\d+.\d+.xip.io$;
root /srv/www/wordpress-default;
error_log /srv/log/wordpress-default/error.log;
access_log /srv/log/wordpress-default/access.log;
set $upstream {upstream};
include /etc/nginx/nginx-wp-common.conf;
}
`

Hi, did anyone find a quick resolution to this?

I got such output just now; commented on a (possibly) related commit:
Varying-Vagrant-Vagrants/vvv-wordpress-default@e660fc8#commitcomment-20565476

Never mind, the quick fix is removing the set $upstream {upstream}; line.
My box has that line in two files, vvv-auto-wordpress-default-provisioner-837fb619e2bfc47058adcbbca596747e.conf and vvv-auto-wordpress-develop-provisioner-ef9283aaee9eec30b285691c96257090.conf , I had to remove it from both.

my wp sites work fine, so I can keep working on my stuff, unblocked.

though nginx, when starting, spills out these warnings I definitely haven't seen before:
==> default: nginx: [warn] conflicting server name "local.wordpress.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name ".local.wordpress.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name "src.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name ".src.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name "build.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name ".build.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name "local.wordpress.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name ".local.wordpress.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name "src.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name ".src.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name "build.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name ".build.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name "local.wordpress.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name ".local.wordpress.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name "src.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name ".src.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name "build.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name ".build.wordpress-develop.dev" on 0.0.0.0:80, ignored
==> default: nginx: [warn] conflicting server name "local.wordpress.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name ".local.wordpress.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name "src.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name ".src.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name "build.wordpress-develop.dev" on 0.0.0.0:443, ignored
==> default: nginx: [warn] conflicting server name ".build.wordpress-develop.dev" on 0.0.0.0:443, ignored