Theia: fix installation

This addresses both :
 - some random failures we sometimes have when installing `python-language-server` fail
 - caddy no longer being installed here since nexedi/slapos!821

See merge request nexedi/slapos!828

software/theia/software.cfg

@@ -120,7 +120,7 @@ eggs =
 version = 0.19.0
 recipe = plone.recipe.command
 command =
-  PATH=${git:location}/bin/:$PATH  bash -c "${python3:executable} -m venv ${:location} && \
+  PATH=${git:location}/bin/:$PATH  bash -c "${python3:executable} -m venv --clear ${:location} && \
     . ${:location}/bin/activate && \
     pip install -r ${python-language-server-requirements.txt:output}"
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
@@ -322,7 +322,7 @@ golang = ${golang1.14:location}
 
 [gowork.goinstall]
 command =
-  bash -c ". ${gowork:env.sh} && GO111MODULE=on go get golang.org/x/tools/gopls@v0.4.3"
+  bash -c ". ${gowork:env.sh} && GO111MODULE=on go get golang.org/x/tools/gopls@v0.4.3 && cd ${go_github.com_caddyserver_caddy:location} && GO111MODULE=on go install -v github.com/caddyserver/caddy/..."
 
 
 [cli-utilities]