Try #10:

Project.toml

@@ -20,15 +20,17 @@ AWSCore = "0.5.2, 0.6"
 AWSSDK = "0.2, 0.3, 0.4, 0.5"
 AWSTools = "0.3.1, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1"
 AutoHashEquals = "0.2.0"
+Git_jll = "2.27"
 HTTP = "0.8.1"
 Memento = "0.7, 0.8, 0.9, 0.10, 0.11, 0.12, 0.13, 1"
 Mocking = "0.7"
 OrderedCollections = "1.4"
 julia = "1"
 
 [extras]
+Git_jll = "f8c6e375-362e-5223-8a59-34ff63f689eb"
 HTTP = "cd3eb016-35fb-5094-929b-558a96fad6f3"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["HTTP", "Test"]
+test = ["Git_jll", "HTTP", "Test"]

test/runtests.jl

@@ -6,6 +6,7 @@ using AWSSDK.CloudWatchLogs: get_log_events
 using AWSTools.CloudFormation: stack_output
 using AWSTools.EC2: instance_region
 using Dates
+using Git_jll
 using HTTP: HTTP
 using Memento
 using Memento.TestUtils: @test_log, @test_nolog
@@ -14,6 +15,19 @@ using Test
 
 Mocking.activate()
 
+function julia_versions()
+    output = withenv(
+        "GIT_SSL_CAINFO" => joinpath(dirname(Sys.BINDIR), "share", "julia", "cert.pem"),
+        "GIT_EXEC_PATH" => joinpath(Git_jll.artifact_dir, "libexec", "git-core"),
+    ) do
+        git() do git_path
+            read(`$git_path ls-remote --tags https://github.com/JuliaLang/julia`, String)
+        end
+    end
+    tags = split(replace(output, r".*\/" => ""))
+    return VersionNumber.(filter!(v -> !endswith(v, "^{}"), tags))
+end
+
 # Controls the running of various tests: "local", "batch"
 const TESTS = strip.(split(get(ENV, "TESTS", "local"), r"\s*,\s*"))
 
@@ -25,10 +39,7 @@ const JOB_TIMEOUT = 900
 const LOG_TIMEOUT = 30
 
 const JULIA_BAKED_IMAGE = let
-    output = read(`git ls-remote --tags https://github.com/JuliaLang/julia`, String)
-    tags = split(replace(output, r".*\/" => ""))
-    versions = VersionNumber.(filter(v -> !endswith(v, "^{}"), tags))
-    latest_version = maximum(versions)
+    latest_version = maximum(julia_versions())
     docker_tag = VERSION > latest_version ? "nightly" : "$VERSION"
 
     "468665244580.dkr.ecr.us-east-1.amazonaws.com/julia-baked:$docker_tag"