DepthGenerator: remove redundant depth check

DepthGenerator: remove redundant depth check

In DepthGenerator, commits are always added to the "pending" queue
either at depth 0 (in the constructor) or after a depth check (in
next()), so it is redundant to check for depth after removing them from
the queue. Remove the check.

This redundancy seems to have been present since the introduction of
server-side shallow clone support in commit 9952223e06 ("Implement
server support for shallow clones", 2011-08-21).

Change-Id: Iad334935293367400c2901a25c0f4bf36c437cf2
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>