Let landmines print something when run as part of `gclient sync`.
Let landmines print something when run as part of `gclient sync`.

(Maybe only needed on Windows.)

Landmines take unusably long when they run on Windows, and if this
prints the diff I can ctrl-c, manually apply that diff to
.landmines, and then runhooks again :-/

BUG=none

Review-Url: https://codereview.chromium.org/1947523002
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#391291}

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