libdpkg: Mark the command_get_pager() tests on a tty as TODO

The build daemon environment does not expose a controlling terminal.
Mark these as possibly failing and as such non-fatal.

debian/changelog

@@ -16,6 +16,8 @@ dpkg (1.17.9) UNRELEASED; urgency=low
     Although this should not have security implications as the buffer is
     surrounded by two arrays (so those catch accesses even if the stack
     grows up or down), and we are compiling with -fstack-protector anyway.
+  * Mark the command_get_pager() tests on a tty as TODO for now, so that
+    we do not get failures on build daemons.
 
   [ Updated scripts translations ]
   * French (Steve Petruzzello). Closes: #746350

lib/dpkg/test/t-command.c

@@ -225,14 +225,16 @@ test_command_pager(void)
 	int origfd = dup(STDOUT_FILENO);
 
 	/* Test stdout being a tty. */
-	test_dup_file(STDOUT_FILENO, "/dev/tty", O_WRONLY);
-	setenv("PAGER", "test-pager", 1);
-	pager = command_get_pager();
-	unsetenv("PAGER");
-	default_pager = command_get_pager();
-	dup2(origfd, STDOUT_FILENO);
-	test_str(pager, ==, "test-pager");
-	test_str(default_pager, ==, DEFAULTPAGER);
+	test_todo_block("environment might not expose controlling terminal") {
+		test_dup_file(STDOUT_FILENO, "/dev/tty", O_WRONLY);
+		setenv("PAGER", "test-pager", 1);
+		pager = command_get_pager();
+		unsetenv("PAGER");
+		default_pager = command_get_pager();
+		dup2(origfd, STDOUT_FILENO);
+		test_str(pager, ==, "test-pager");
+		test_str(default_pager, ==, DEFAULTPAGER);
+	}
 
 	/* Test stdout not being a tty. */
 	test_dup_file(STDOUT_FILENO, "/dev/null", O_WRONLY);