alt Hacker NewsMerge conflicts on binary files are typically unresolvable in practice because the editing tools don't normally have the ability to compare files. This leads to one of the two divergent sets of changes getting lost. That's why great VCSes allow file locking: locks are a communication tool between team members to avoid losing work.
a great VCS wouldn't require locking or pre-communication; it would simply refuse to even try to merge assets it couldn't deal with, and leave the result of a merge in a state where the user can reasonably address it (in this case, presumably just "yes, use mine" or "no, use the one already in the repo" and perhaps "use mine but rename it").