api: up emerge backtrack limit from 30 to 50

BUG=b:296792476
TEST=yolo

Change-Id: I22f6f0ed2084a8b9e80ccb2d3b1fc9a3ed18caf7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4807718
Tested-by: Sergey Frolov <sfrolov@google.com>
Auto-Submit: Sergey Frolov <sfrolov@google.com>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Sergey Frolov <sfrolov@google.com>
diff --git a/api/controller/sysroot.py b/api/controller/sysroot.py
index a1b60f0..2797bd3 100644
--- a/api/controller/sysroot.py
+++ b/api/controller/sysroot.py
@@ -27,7 +27,7 @@
 
 _ACCEPTED_LICENSES = "@CHROMEOS"
 
-DEFAULT_BACKTRACK = 30
+DEFAULT_BACKTRACK = 50
 
 
 def _GetGomaLogDirectory():