From 3ad6340c13c2b03ab3d7a44963f8adb82f66eec3 Mon Sep 17 00:00:00 2001
From: Fabian Neumann <fabian.neumann@outlook.de>
Date: Fri, 4 Dec 2020 18:53:12 +0100
Subject: [PATCH] travis: correctly constrain version

---
 .travis.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 5b06a779..75a82378 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,7 +24,7 @@ before_install:
   - conda activate pypsa-eur
 
   # install open-source solver
-  - mamba install -c conda-forge glpk ipopt<3.13.3
+  - mamba install -c conda-forge glpk ipopt'<3.13.3'
 
   # list packages for easier debugging
   - conda list