Try just removing sh.exe outright

Hilarious things happen in Travis when /bin goes away

.travis.yml

@@ -14,9 +14,8 @@ before_script:
   - rustup update
   - rustup component add clippy
   - rustup component add rustfmt
-  # CMake doesn't like `sh.exe` being available on Windows,
-  # and since we don't use it elsewhere, just remove from PATH
-  - export PATH="${PATH/:\/bin/}"
+  # CMake doesn't like `sh.exe` being on the PATH,
+  - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then rm "C:/Program Files/Git/usr/bin/sh.exe"; fi
 
 script:
   - cargo clippy --all