fixup! Fix Travis test for build command.

.travis.yml

@@ -43,9 +43,17 @@ script:
   - tox
   - |
     if [[ $TOXENV == "build" ]]; then
-     # Check that exactly one tarball and one wheel are created
-     [ $(find . -iwholename 'dist/*.tar.gz' | wc -l) -eq 1 ]
-     [ $(find . -iwholename 'dist/*.whl' | wc -l) -eq 1 ]
+      exactly_one() {
+        value=$(find . -iwholename $1 | wc -l)
+        if [ $value -neq 1 ]; then
+          echo "Found $value instances of $1, not 1"
+          exit 1
+        fi
+      }
+
+      # Check that exactly one tarball and one wheel are created
+      exactly_one 'dist/*.tar.gz'
+      exactly_one 'dist/*.whl'
     fi
 
 after_success: