ci/circle: speed up tests / coverage

Instead of running the testsuite twice when coverage is need,
only run it once (without filtering out `nocov` tests): with
`cluacov` installed, it's only 50% slower than a normal run.

.ci/after_success.sh

@@ -7,11 +7,9 @@ source "${CI_DIR}/common.sh"
 set +e
 
 if [ -z "${CIRCLE_PULL_REQUEST}" ] && [ "${CIRCLE_BRANCH}" = 'master' ]; then
-    travis_retry make --assume-old=all coverage
-    pushd install/koreader && {
+    echo -e "\\n${ANSI_GREEN}Uploading coverage."
+    cd install/koreader && {
         # see https://github.com/codecov/example-lua
         bash <(curl -s https://codecov.io/bash)
-    } && popd || exit
-else
-    echo -e "\\n${ANSI_GREEN}Not on official master branch. Skipping coverage."
+    }
 fi

.ci/test.sh

@@ -4,6 +4,14 @@ CI_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 # shellcheck source=/dev/null
 source "${CI_DIR}/common.sh"
 
-make testfront --assume-old=all T="-o '${PWD}/test-results.xml'"
+if [[ -z "${CIRCLE_PULL_REQUEST}" ]] && [[ "${CIRCLE_BRANCH}" == 'master' ]]; then
+    # We're on master: do a full testsuite run with coverage.
+    target='coverage'
+else
+    # Pull request / not on master: do a regular testsuite run.
+    target='testfront'
+fi
+
+make "${target}" --assume-old=all T="-o '${PWD}/test-results.xml'"
 
 # vim: sw=4

.circleci/config.yml

@@ -103,11 +103,11 @@ jobs:
       - run:
           name: Test
           command: .ci/test.sh
-      # Docs, coverage, and test timing (can we use two outputs at once?); master branch only.
+      # Upload coverage statistics (master branch only).
       - run:
-          name: Coverage
+          name: Uploading coverage
           command: .ci/after_success.sh
-      # By storing the test results CircleCI automatically distributes tests based on execution time.
+      # Store test results for better feedback / insights.
       - store_test_results:
           path: &TESTS_XML test-results.xml
       # CircleCI doesn't make the test results available as artifacts (October 2017).
@@ -129,7 +129,7 @@ jobs:
       - run:
           name: fetch
           command: .ci/fetch.sh
-      # docs, coverage, and test timing (can we use two outputs at once?); master branch only
+      # Docs & translations (master branch only).
       - run:
           name: docs-and-translation
           command: .ci/after_success_docs_translation.sh