Disable fish tests on travis

tests/install.sh

@@ -9,5 +9,7 @@ if python -c 'import sys; sys.exit(1 * (sys.version_info[0] != 2))' ; then
 		pip install unittest2 argparse
 	fi
 fi
-sudo apt-get install -qq screen zsh fish
+sudo apt-get install -qq screen zsh
+# Travis has too outdated fish. It cannot be used for tests.
+# sudo apt-get install fish
 true

tests/test_shells/test.sh

@@ -18,6 +18,8 @@ run_test() {
 
 	test "x$ONLY_SHELL" = "x" || test "x$ONLY_SHELL" = "x$SH" || return 0
 
+	which "${SH}" || return 0
+
 	screen -L -c tests/test_shells/screenrc -d -m -S "$SESNAME" \
 		env LANG=en_US.UTF-8 BINDFILE="$BINDFILE" "$@"
 	screen -S "$SESNAME" -X readreg a tests/test_shells/input.$SH