Make sure that overrides do not affect Vim and IPython

Fixes #1201

tests/run_vim_tests.sh

@@ -29,6 +29,11 @@ else
 	OLD_VIM="$VIM"
 fi
 
+# Define some overrides. These ones must be ignored and do not affect Vim 
+# status/tab lines.
+export POWERLINE_CONFIG_OVERRIDES='common.default_top_theme=ascii'
+export POWERLINE_THEME_OVERRIDES='default.segments.left=[]'
+
 test_script() {
 	local vim="$1"
 	local script="$2"

tests/test_shells/test.sh

@@ -76,6 +76,8 @@ run() {
 		XDG_CONFIG_HOME="$PWD/tests/shell/fish_home" \
 		IPYTHONDIR="$PWD/tests/shell/ipython_home" \
 		PYTHONPATH="${PWD}${PYTHONPATH:+:}$PYTHONPATH" \
+		POWERLINE_CONFIG_OVERRIDES="${POWERLINE_CONFIG_OVERRIDES}" \
+		POWERLINE_THEME_OVERRIDES="${POWERLINE_THEME_OVERRIDES}" \
 		POWERLINE_SHELL_CONTINUATION=$additional_prompts \
 		POWERLINE_SHELL_SELECT=$additional_prompts \
 		POWERLINE_CONFIG_PATHS="$PWD/powerline/config_files" \
@@ -387,11 +389,16 @@ fi
 
 if test "x${ONLY_SHELL}" = "x" || test "x${ONLY_SHELL}" = "xipython" ; then
 	if which ipython >/dev/null ; then
+		# Define some overrides which should be ignored by IPython.
+		POWERLINE_CONFIG_OVERRIDES='common.term_escape_style=fbterm'
+		POWERLINE_THEME_OVERRIDES='in.segments.left=[]'
 		echo "> $(which ipython)"
 		if ! run_test ipython ipython ipython ; then
 			FAILED=1
 			FAIL_SUMMARY="${FAIL_SUMMARY}${NL}T ipython"
 		fi
+		unset POWERLINE_THEME_OVERRIDES
+		unset POWERLINE_CONFIG_OVERRIDES
 	fi
 fi