diff --git a/jobs/swh-environment.yaml b/jobs/swh-environment.yaml
index f5b4e31..a15c16f 100644
--- a/jobs/swh-environment.yaml
+++ b/jobs/swh-environment.yaml
@@ -1,73 +1,75 @@
 - project:
     name: DENV
     display-name: swh-environment
     jobs:
       - "{name}"
 
 - job:
     name: DENV/tests
     description: Run tests for each swh module in development version
     node: swh-sphinx
 
     triggers:
       - timed: "H */6 * * *"
 
     scm:
       - git:
           url: https://forge.softwareheritage.org/source/swh-environment.git
           branches:
             - "*/master"
     wrappers:
       - timeout:
           timeout: 120
           abort: true
       - timestamps
 
     builders:
       - shell: |
           #!/bin/bash
+          # Don't fetch potentially large branches, we only need master
+          sed -i 's/git clone/git clone --single-branch/g' .mrconfig
           # fetch swh repositories
           mr -j 4 -t update
           # setup a virtualenv
           python3 -m venv .venv
           . .venv/bin/activate
           # upgrade pip as default installed version is too outdated to properly
           # install all swh dependencies
           pip install --upgrade pip
           # install dependencies
           ./bin/install
           cd swh-graph
           make java >/dev/null
           cd ../swh-web
           yarn install
           cd ..
           # execute tests in each swh module
           exit_code=0
           for module in $(./bin/ls-py-modules)
           do
               cd $module
               tests_dir=$(echo $module | sed 's/-/\//g')/tests
               if [ -d "$tests_dir" ]
               then
                 # pipe checks and tests output to stdout and log file
                 make check 2>&1 | tee ../$module.log
                 tests_status=${PIPESTATUS[0]}
                 make test 2>&1 | tee -a ../$module.log
                 tests_status=$(($tests_status + ${PIPESTATUS[0]}))
                 # remove log file if tests succeeded
                 if [[ "$tests_status" == "0" ]]
                 then
                   rm -f ../$module.log
                 fi
                 # script must be exited with error when a test suite failed
                 exit_code=$(( tests_status > exit_code ? tests_status : exit_code ))
               fi
               cd ..
           done
 
           exit $exit_code
 
     publishers:
       - archive:
           artifacts: "*.log"
           allow-empty: true