Add retry in wget for debootstrap

Bug: n/a
Test: kokoro
Change-Id: I7ed864c6675cd461152e8561736efe0c789c091e
diff --git a/build/debian/build.sh b/build/debian/build.sh
index a9b5e7a..8c17514 100755
--- a/build/debian/build.sh
+++ b/build/debian/build.sh
@@ -55,6 +55,7 @@
 		qemu-user-static
 
         sed -i s/losetup\ -f/losetup\ -P\ -f/g /usr/sbin/fai-diskimage
+        sed -i 's/wget \$/wget -t 0 \$/g' /usr/share/debootstrap/functions
 
         apt install --no-install-recommends --assume-yes curl
         # just for testing