travis: fetch only tags

The original `git pull` would try to pull & merge changes from the
master branch, which breaks CI runs on PRs based on non-master branches

diff --git a/.travis.yml b/.travis.yml
index 90ea8e90625b7d4c442a40e079ae5c7afbfa6424..37002e9ac3accaf6465ce5564b856a08f257c184 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -30,7 +30,7 @@ before_script:
     sudo modprobe kvm-intel nested=1 || :
     sudo modprobe kvm-amd nested=1 || :
     dmesg | tail || :
-  - git pull --depth=100
+  - git fetch --tags --unshallow
   - |
     git describe --abbrev=0 --tags || :
     git describe --tags || :