Make test work with upstream cbehave
(tinydir bundles a modified version)

diff --git a/tests/file_open_test.c b/tests/file_open_test.c
index 09b856e..92b13ca 100644
--- a/tests/file_open_test.c
+++ b/tests/file_open_test.c
@@ -4,6 +4,11 @@
 #include "cbehave.h"
 #include "util.h"
 
+#define ASSERT(cond, ret) \
+if (!(cond)) {\
+    cbehave_feature_return(__FILE__, __LINE__, ret, _state); \
+    goto _feature_over; \
+}\
 
 FEATURE(file_open, "File open")
 	SCENARIO("Open file in current directory")
@@ -34,4 +39,7 @@ FEATURE(file_open, "File open")
 	SCENARIO_END
 FEATURE_END
 
-CBEHAVE_RUN("File open:", TEST_FEATURE(file_open))
+int main(void) {
+	cbehave_feature _cfeatures[] = {{feature_idx(file_open)}};
+	return cbehave_runner("File open:", _cfeatures);
+}
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<tr><td><span title='2018-04-08 17:48:33 +0200'>2018-04-08</span></td><td><a href='/guix/commit/build-aux/cuirass/hydra-to-cuirass.scm?id=a1ec7540be9b30593f5e83e36a0e83b1bcf337f1'>cuirass: Factorize hydra-to-cuirass CI job translation.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/cuirass/gnu-system.scm: Move code to...
* build-aux/cuirass/hydra-to-cuirass.scm: ... here, and include it.
* Makefile.am (EXTRA_DIST): Add 'build-aux/cuirass/hydra-to-cuirass.scm'
and 'build-aux/cuirass/gnu-system.scm'.
</span></span></td><td>Ludovic Courtès</td></tr>