Tested on devenv_3238, tried to create application with invalid git url, still met "node execution failure" error, log is as following:

2013-05-17 05:02:00.319 [INFO ] Started POST "/app/console/applications" for 66.187.233.202 at 2013-05-17 05:02:00 -0400 (pid:1957)
2013-05-17 05:02:00.364 [INFO ] Processing by ApplicationsController#create as HTML (pid:1957)
2013-05-17 05:02:00.366 [INFO ] Parameters: {"utf8"=>"✓", "authenticity_token"=>"vox24M65+GiVPHXQOER4sWpcyeffGVcaUK+K+55X32k=", "advanced"=>"true", "unlock"=>"false", "application"=>{"application_type"=>"cart!ruby-1.9", "name"=>"sdfhsdfg", "initial_git_url"=>"sdfhsdfg", "gear_profile"=>"small", "cartridges"=>["ruby-1.9"], "scale"=>"false"}} (pid:1957)
2013-05-17 05:02:00.371 [DEBUG] Session contents: {"ticket"=>"YWdh", "api_ticket"=>"104a4ba881cc7cfb19ab1507d60f1a8aece796bd11d44345cc5f75e03524cc1f", "login"=>"aga", "streamline_type"=>:full, "terms"=>true, "session_id"=>"99aeaeeaa219e0146648684197966de7", "currency_cd"=>"usd", "_csrf_token"=>"vox24M65+GiVPHXQOER4sWpcyeffGVcaUK+K+55X32k="} (pid:1957)
2013-05-17 05:02:00.104 [DEBUG] OpenShift API (62.4ms) get https://localhost:443/broker/rest/user.json [ code: 200 ] (pid:1957)
2013-05-17 05:02:00.212 [DEBUG] OpenShift API (104.0ms) get https://localhost:443/broker/rest/domains.json [ code: 200 ] (pid:1957)
2013-05-17 05:02:28.661 [DEBUG] OpenShift API (28445.6ms) post https://localhost:443/broker/rest/domains/fghsdg/applications.json [ code: 500 ] (pid:1957)
2013-05-17 05:02:28.667 [DEBUG] Server error: : #-1: Unable to complete the requested operation due to: Node execution failure (invalid exit code from node).  If the problem persists please contact Red Hat support..
Reference ID: dd43ea50b1a79983b54caef4e79b3dfb (pid:1957)
2013-05-17 05:02:28.667 [DEBUG] Found errors on the response object: {:base=>["Unable to complete the requested operation due to: Node execution failure (invalid exit code from node).  If the problem persists please contact Red Hat support..\nReference ID: dd43ea50b1a79983b54caef4e79b3dfb"]} (pid:1957)
2013-05-17 05:02:28.668 [DEBUG] #<ActiveResource::Errors:0x000000043c8b70 @base=#<Application:0x000000045e1a88 @as=#<WebUser::Mock:0x000000045712b0 @rhlogin="aga", @ticket="YWdh", @api_ticket="104a4ba881cc7cfb19ab1507d60f1a8aece796bd11d44345cc5f75e03524cc1f", @streamline_type=:full, @errors=#<ActiveModel::Errors:0x00000004578c18 @base=#<WebUser::Mock:0x000000045712b0 ...>, @messages={}>>, @attributes={"cartridges"=>["ruby-1.9"], "name"=>"sdfhsdfg", "initial_git_url"=>"sdfhsdfg", "gear_profile"=>"small", "scale"=>"false"}, @prefix_options={:domain_id=>"fghsdg"}, @persisted=false, @errors=#<ActiveResource::Errors:0x000000043c8b70 ...>, @changed_attributes=

Set it medium for it will confuse user when debugging problem.

Rest API must inform us of real errors

The Rest API does return the right error message.  If you can still reproduce the bug please assign back to UI team.

curl -k https://localhost/broker/rest/domains/lnader/applications -d "name=app3" -d "cartridge=php-5.3" -d "initial_git_url=hgdhdfkhdfk" -u lnader:ppp | python -mjson.tool
{
    "data": null, 
    "errors": {}, 
    "messages": [
        {
            "exit_code": 216, 
            "field": "initial_git_url", 
            "severity": "error", 
            "text": "Invalid initial git URL"
        }
    ], 
    "status": "unprocessable_entity", 
    "supported_api_versions": [
        1.0, 
        1.1, 
        1.2, 
        1.3, 
        1.4, 
        1.5
    ], 
    "type": null, 
    "version": 1.5
}

tested on devenv_3277 and works as normal, so verified it, thanks!