Ignore SIGPIPE, it causes the test-executing subprocess to bail out

before all diagnostics have been gathered.

bin/varnishtest/vtc.c

@@ -32,6 +32,7 @@
 #include <sys/wait.h>
 
 #include <ctype.h>
+#include <signal.h>
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -526,6 +527,8 @@ exec_file(const char *fn, const char *script, const char *tmpdir,
 	FILE *f;
 	struct extmacro *m;
 
+	signal(SIGPIPE, SIG_IGN);
+
 	vtc_loginit(logbuf, loglen);
 	vltop = vtc_logopen("top");
 	AN(vltop);