provisioners/docker: search for Docker in multiple paths [GH-4580]

CHANGELOG.md

@@ -4,6 +4,7 @@ BUG FIXES:
 
   - providers/virtualbox: Show a human-friendly error if VirtualBox didn't
       clean up an existing VM. [GH-4681]
+  - provisioners/docker: Search for docker binary in multiple places. [GH-4580]
 
 ## 1.6.5 (September 4, 2014)
 

plugins/provisioners/docker/cap/linux/docker_installed.rb

@@ -4,7 +4,19 @@ module VagrantPlugins
       module Linux
         module DockerInstalled
           def self.docker_installed(machine)
-            machine.communicate.test("test -f /usr/bin/docker", sudo: true)
+            paths = [
+              "/usr/bin/docker",
+              "/usr/local/bin/docker",
+              "/usr/sbin/docker",
+            ]
+
+            paths.each do |p|
+              if machine.communicate.test("test -f #{p}", sudo: true)
+                return true
+              end
+            end
+
+            return false
           end
         end
       end