beamPackages.lfe: avoid throwing for incompatibility in CI

Same reasoning as commit before.

pkgs/development/interpreters/lfe/generic-builder.nix

@@ -1,4 +1,5 @@
 {
+  config,
   lib,
   fetchFromGitHub,
   erlang,
@@ -37,6 +38,8 @@ let
 
   mainVersion = versions.major (getVersion erlang);
 
+  maxAssert = versionAtLeast maximumOTPVersion mainVersion;
+
   proper = buildHex {
     name = "proper";
     version = "1.4.0";
@@ -45,82 +48,85 @@ let
   };
 
 in
-assert (assertMsg (versionAtLeast maximumOTPVersion mainVersion)) ''
-  LFE ${version} is supported on OTP <=${maximumOTPVersion}, not ${mainVersion}.
-'';
-
-buildRebar3 {
-  name = baseName;
-
-  inherit src version;
-
-  nativeBuildInputs = [
-    makeWrapper
-    erlang
-  ];
-  beamDeps = [ proper ];
-  patches = [
-    ./fix-rebar-config.patch
-    ./dedup-ebins.patch
-  ] ++ patches;
-  doCheck = true;
-  checkTarget = "travis";
-
-  makeFlags = [
-    "-e"
-    "MANDB=''"
-    "PREFIX=$$out"
-  ];
-
-  # These installPhase tricks are based on Elixir's Makefile.
-  # TODO: Make, upload, and apply a patch.
-  installPhase = optionalString (versionOlder version "1.3") ''
-    local libdir=$out/lib/lfe
-    local ebindir=$libdir/ebin
-    local bindir=$libdir/bin
-
-    rm -Rf $ebindir
-    install -m755 -d $ebindir
-    install -m644 _build/default/lib/lfe/ebin/* $ebindir
-
-    install -m755 -d $bindir
-
-    for bin in bin/lfe{,c,doc,script}; do install -m755 $bin $bindir; done
-
-    install -m755 -d $out/bin
-    for file in $bindir/*; do ln -sf $file $out/bin/; done
+if !config.allowAliases && !maxAssert then
+  # Don't throw without aliases to not break CI.
+  null
+else
+  assert assertMsg maxAssert ''
+    LFE ${version} is supported on OTP <=${maximumOTPVersion}, not ${mainVersion}.
   '';
+  buildRebar3 {
+    name = baseName;
 
-  # Thanks again, Elixir.
-  postFixup = ''
-    # LFE binaries are shell scripts which run erl and lfe.
-    # Add some stuff to PATH so the scripts can run without problems.
-    for f in $out/bin/*; do
-      wrapProgram $f \
-        --prefix PATH ":" "${
-          makeBinPath [
-            erlang
-            coreutils
-            bash
-          ]
-        }:$out/bin"
-      substituteInPlace $f --replace "/usr/bin/env" "${coreutils}/bin/env"
-    done
-  '';
+    inherit src version;
 
-  meta = with lib; {
-    description = "Best of Erlang and of Lisp; at the same time!";
-    longDescription = ''
-      LFE, Lisp Flavoured Erlang, is a lisp syntax front-end to the Erlang
-      compiler. Code produced with it is compatible with "normal" Erlang
-      code. An LFE evaluator and shell is also included.
+    nativeBuildInputs = [
+      makeWrapper
+      erlang
+    ];
+    beamDeps = [ proper ];
+    patches = [
+      ./fix-rebar-config.patch
+      ./dedup-ebins.patch
+    ] ++ patches;
+    doCheck = true;
+    checkTarget = "travis";
+
+    makeFlags = [
+      "-e"
+      "MANDB=''"
+      "PREFIX=$$out"
+    ];
+
+    # These installPhase tricks are based on Elixir's Makefile.
+    # TODO: Make, upload, and apply a patch.
+    installPhase = optionalString (versionOlder version "1.3") ''
+      local libdir=$out/lib/lfe
+      local ebindir=$libdir/ebin
+      local bindir=$libdir/bin
+
+      rm -Rf $ebindir
+      install -m755 -d $ebindir
+      install -m644 _build/default/lib/lfe/ebin/* $ebindir
+
+      install -m755 -d $bindir
+
+      for bin in bin/lfe{,c,doc,script}; do install -m755 $bin $bindir; done
+
+      install -m755 -d $out/bin
+      for file in $bindir/*; do ln -sf $file $out/bin/; done
     '';
 
-    homepage = "https://lfe.io";
-    downloadPage = "https://github.com/rvirding/lfe/releases";
+    # Thanks again, Elixir.
+    postFixup = ''
+      # LFE binaries are shell scripts which run erl and lfe.
+      # Add some stuff to PATH so the scripts can run without problems.
+      for f in $out/bin/*; do
+        wrapProgram $f \
+          --prefix PATH ":" "${
+            makeBinPath [
+              erlang
+              coreutils
+              bash
+            ]
+          }:$out/bin"
+        substituteInPlace $f --replace "/usr/bin/env" "${coreutils}/bin/env"
+      done
+    '';
 
-    license = licenses.asl20;
-    teams = [ teams.beam ];
-    platforms = platforms.unix;
-  };
-}
+    meta = with lib; {
+      description = "Best of Erlang and of Lisp; at the same time!";
+      longDescription = ''
+        LFE, Lisp Flavoured Erlang, is a lisp syntax front-end to the Erlang
+        compiler. Code produced with it is compatible with "normal" Erlang
+        code. An LFE evaluator and shell is also included.
+      '';
+
+      homepage = "https://lfe.io";
+      downloadPage = "https://github.com/rvirding/lfe/releases";
+
+      license = licenses.asl20;
+      teams = [ teams.beam ];
+      platforms = platforms.unix;
+    };
+  }