Large patch/diff refuses to apply

I'm doing a large amount of change to ixgbe(4) in support of IFLIB
implementations and running into failures when trying to apply large
diffs.  This is causing phabricator reviews to be unuseable as well.

I've setup two trees to test this.  The first tree is used to generate
the diff and the second (vanilla) is used to apply the diff.  The entire
patch fails to apply, so I'm assuming that the size of the diff is
failing because of a sanity check or something.

https://people.freebsd.org/~sbruno/test.diff

% svn stat sys/dev/ixgbe/if_ix.c
M       sys/dev/ixgbe/if_ix.c

% svn diff sys/dev/ixgbe/if_ix.c > ~/test.diff


% cd ../vanilla/

% patch -p0 < ~/test.diff
Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|Index: sys/dev/ixgbe/if_ix.c
|===================================================================
|--- sys/dev/ixgbe/if_ix.c      (revision 306673)
|+++ sys/dev/ixgbe/if_ix.c      (working copy)
--------------------------
Patching file sys/dev/ixgbe/if_ix.c using Plan A...
Hunk #1 failed at 1.
1 out of 1 hunks failed--saving rejects to sys/dev/ixgbe/if_ix.c.rej
done

% ls -l sys/dev/ixgbe/if_ix.c*
-rw-r--r--  1 sbruno  wheel  166692 Oct  6 06:41 sys/dev/ixgbe/if_ix.c
-rw-r--r--  1 sbruno  wheel  166692 Oct  6 06:37 sys/dev/ixgbe/if_ix.c.orig
-rw-r--r--  1 sbruno  wheel  172779 Oct  6 06:41 sys/dev/ixgbe/if_ix.c.rej

% svn stat sys/dev/ixgbe/
?       sys/dev/ixgbe/if_ix.c.orig