[build_dockerfile] Fixing bug in manifest parse #32
[build_dockerfile] Fixing bug in manifest parse #32

After modification that adds support Dockerfiles with an error image option was introduced once the system was attempting to obtain a name for the image (which is the compound mid) before having a defined metadata.

azukiapp/azk,saitodisse/azk,slobo/azk,renanmpimentel/azk,gullitmiranda/azk,agendor/azk,Klaudit/azk,teodor-pripoae/azk,agendor/azk,heitortsergent/azk,azukiapp/azk,juniorribeiro/azk,marcusgadbem/azk,fearenales/azk,gullitmiranda/azk,teodor-pripoae/azk,nuxlli/azk,juniorribeiro/azk,nuxlli/azk,slobo/azk,fearenales/azk,renanmpimentel/azk,saitodisse/azk,heitortsergent/azk,marcusgadbem/azk,Klaudit/azk