test-equal-marks-insert fails

I tried building from git master on Debian Unstable and one of the build tests failed:

```
ERROR:../dist-unpack/text-engine-0.1.0/test/replace.c:401:test_equal_marks_insert:
assertion failed (text == "abcdehellofghij1234567890!@#$%^&*()"): (
"abcdefghellohij1234567890!@#$%^&*()" ==
"abcdehellofghij1234567890!@#$%^&*()"
)

(test program exited with status code -6)
````