New commit detected on ManageIQ/manageiq/gaprindashvili:
https://github.com/ManageIQ/manageiq/commit/0ae390bc3049e2121a125b8b48dc49eb659a514f

commit 0ae390bc3049e2121a125b8b48dc49eb659a514f
Author:     Greg McCullough <gmccullo>
AuthorDate: Thu Jan 4 09:40:55 2018 -0500
Commit:     Satoe Imaishi <simaishi>
CommitDate: Thu Jan 4 17:55:33 2018 -0500

    Merge pull request #16736 from masayag/vm_template_limits
    
    Set limits for VM and Template names and descriptions
    (cherry picked from commit bf689eba47174db57344d593e53bb3cf28677c95)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1531292

 .../miq_dialogs/miq_provision_redhat_dialogs_clone_to_template.yaml   | 4 ++--
 .../dialogs/miq_dialogs/miq_provision_redhat_dialogs_clone_to_vm.yaml | 4 ++--
 .../dialogs/miq_dialogs/miq_provision_redhat_dialogs_template.yaml    | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

VM/Template name was suggested by Greg to stay limited to 40 chars on CFME side to avoid RHV version specific logic, but in the commit [1] VM/template Name was also updated to 255 chars limit. 
As Ilanit specifies in the first comment, RHV limits VM/template name to 64 chars, so attempt to provision VM with name longer than 64 chars fails.

[1] https://github.com/ManageIQ/manageiq/commit/0ae390bc3049e2121a125b8b48dc49eb659a514f

Radim - As discussed here https://github.com/ManageIQ/manageiq/pull/16736#issuecomment-355107499 I suggested that we use the larger value now as that will be the supported value going forward.

If a user has a need to enforce the 64 character limit they can do that by modifying the dialog to meet their needs.  This option has been available for a long time in the dialogs.

Greg - Thank you for explaining.

Verified in RHV 4.1.8, CFME 5.9.0.16 that VM/Template name/description is updated to 255 chars.