Merge pull request #14672 from NixOS/fix-13948

libfetchers: Fix fetchGit with ref = "HEAD"

Author: Ericson2314

src/libfetchers/git.cc

@@ -836,7 +836,7 @@ struct GitInputScheme : InputScheme
                     auto fetchRef = getAllRefsAttr(input)             ? "refs/*:refs/*"
                                     : input.getRev()                  ? input.getRev()->gitRev()
                                     : ref.compare(0, 5, "refs/") == 0 ? fmt("%1%:%1%", ref)
-                                    : ref == "HEAD"                   ? ref
+                                    : ref == "HEAD"                   ? "HEAD:HEAD"
                                                                       : fmt("%1%:%1%", "refs/heads/" + ref);
 
                     repo->fetch(repoUrl.to_string(), fetchRef, shallow);

tests/functional/fetchGit.sh

@@ -228,6 +228,10 @@ path8=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$rep
 rev4=$(git -C "$repo" rev-parse HEAD)
 rev4_nix=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"HEAD\"; }).rev")
 [[ $rev4 = "$rev4_nix" ]]
+export _NIX_FORCE_HTTP=1
+rev4_nix=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"HEAD\"; }).rev")
+[[ $rev4 = "$rev4_nix" ]]
+unset _NIX_FORCE_HTTP
 
 # The name argument should be handled
 path9=$(nix eval --impure --raw --expr "(builtins.fetchGit { url = \"file://$repo\"; ref = \"HEAD\"; name = \"foo\"; }).outPath")