fix: json mime type on bionic

.travis.yml

@@ -5,7 +5,5 @@ addons:
       - qemu-utils
       - parted
       - jq
-      - libmagic-mgc
 script:
   - ./test.sh
-  - file -b --mime-type tests/data/streams.json

tests/maas.sh

@@ -5,7 +5,14 @@ function test_stream()
     local mimetype
     get_streams
     mimetype="$(file -b --mime-type "$streams")"
+    [ "$(lsb_release -cs)" == "bionic" ] && startSkipping
     assertEquals "application/json" "$mimetype"
+    isSkipping && endSkipping
+    [ "$(lsb_release -cs)" == "focal" ] && startSkipping
+    assertEquals "text/plain" "$mimetype"
+    isSkipping && endSkipping
+    jq . "$streams" &> /dev/null
+    assertEquals 0 "$?"
     cleanup_temp
 }
 
@@ -38,4 +45,4 @@ function setUp()
 }
 
 # Load shUnit2.
-. /usr/bin//shunit2
+. /usr/bin/shunit2