Patch to send compile to remote machine if Linux arch does match

compile_patch.diff

diff --git a/nixops/backends/__init__.py b/nixops/backends/__init__.py
index 86ed0f4..c52e9d3 100644
--- a/nixops/backends/__init__.py
+++ b/nixops/backends/__init__.py
@@ -93,6 +93,17 @@ class MachineState(nixops.resources.ResourceState):
         except nixops.ssh_util.SSHCommandFailed:
             return None
 
+    def get_os_arch(self):
+        """Get the machine's OS archicture."""
+        try:
+            res = self.run_command("uname -m", capture_stdout=True, timeout=15).rstrip()
+            assert len(res) >= 3
+            return res
+        except nixops.ssh_util.SSHConnectionFailed:
+            return None
+        except nixops.ssh_util.SSHCommandFailed:
+            return None
+
     # FIXME: Move this to ResourceState so that other kinds of
     # resources can be checked.
     def check(self):
diff --git a/nixops/deployment.py b/nixops/deployment.py
index b504577..61128a6 100644
--- a/nixops/deployment.py
+++ b/nixops/deployment.py
@@ -551,7 +551,7 @@ class Deployment(object):
                 })
 
 
-                # Add SSH public host keys for all machines in network  
+                # Add SSH public host keys for all machines in network
                 for m2 in active_machines.itervalues():
                     if hasattr(m2, 'public_host_key') and m2.public_host_key:
                         # Using references to files in same tempdir for now, until NixOS has support
@@ -627,10 +627,21 @@ class Deployment(object):
 
         names = map(lambda m: m.name, selected)
 
+        # get unique values for all of the possible arches (or None if)
+        # arch can not be retrieved
+        machine_arches = set(machine.get_os_arch() for machine in selected)
+        # if we could retrieve some of the target machine arches or if any
+        # targer machine's archs is different then the host machine then
+        # always build remove
+        build_remote = False
+        if len(machine_arches) > 1 or (platform.machine() not in machine_arches):
+            build_remote = True
+            self.logger.log("building everything on target machine(s)")
+
         # If we're not running on Linux, then perform the build on the
         # target machines.  FIXME: Also enable this if we're on 32-bit
         # and want to deploy to 64-bit.
-        if platform.system() != 'Linux' and os.environ.get('NIX_REMOTE') != 'daemon':
+        if build_remote == True and os.environ.get('NIX_REMOTE') != 'daemon':
             if os.environ.get('NIX_REMOTE_SYSTEMS') == None:
                 remote_machines = []
                 for m in sorted(selected, key=lambda m: m.index):