Fix travis failure if previous travis run on branch failed to build

Author: TheBlueMatt

.travis.yml

@@ -12,7 +12,7 @@ before_install:
 
 script:
   - RUSTFLAGS="-C link-dead-code" cargo build --verbose
-  - rm target/debug/lightning-* # Make sure we drop old test binaries
+  - rm -f target/debug/lightning-* # Make sure we drop old test binaries
   - RUSTFLAGS="-C link-dead-code" cargo test --verbose
   - if [ "$(rustup show | grep default | grep 1.34.2)" != "" ]; then cd fuzz && cargo test --verbose && ./travis-fuzz.sh; fi
   - if [ "$(rustup show | grep default | grep stable)" != "" ]; then cd net-tokio && cargo build --verbose && cd ..; fi