Revert "Merge pull request #25131 from javierhonduco/javierhonduco/clone_depth_to_1"

This reverts commit acf0bb3f, reversing
changes made to c5b766a9.

Travis can only build a commit it can clone; without any clone depth,
all branch builds error as soon as there's a newer commit present.

.travis.yml

@@ -88,6 +88,3 @@ notifications:
     on_failure: always
     rooms:
       - secure: "YA1alef1ESHWGFNVwvmVGCkMe4cUy4j+UcNvMUESraceiAfVyRMAovlQBGs6\n9kBRm7DHYBUXYC2ABQoJbQRLDr/1B5JPf/M8+Qd7BKu8tcDC03U01SMHFLpO\naOs/HLXcDxtnnpL07tGVsm0zhMc5N8tq4/L3SHxK7Vi+TacwQzI="
-
-git:
-  depth: 1