Author: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Mon Aug 18 07:09:07 2025 +0100

Fix(builder): Align Unix git mirror logic with Windows version

The git helper script for Unix (`git_helper_sh`) used a separate
`git fetch` and `git update-ref` sequence to update the local mirror.
This was inconsistent with the Windows script (`git_helper_bat`), which
uses a more robust, single `git fetch` command with a refspec.

This inconsistency could lead to a failure loop where the builder would
repeatedly try to fetch a local reference from the upstream remote,
causing the process to get stuck.

This commit modifies the `git_helper_sh` to use the same refspec
approach as the Windows script, fetching the remote ref directly into
the local `ref-<hash>` ref. This makes the mirroring logic consistent
across platforms and resolves the infinite loop issue.


diff --git a/src/builder/b-mirror.c b/src/builder/b-mirror.c
index 05bb29a..9c63b3a 100644
--- a/src/builder/b-mirror.c
+++ b/src/builder/b-mirror.c
@@ -57,12 +57,8 @@ static const char * const git_helper_sh =
 	"    if [ ! -d \"$MIRROR_PATH/.git\" ]; then\n"
 	"        git init --bare \"$MIRROR_PATH\"\n"
 	"    fi\n"
-	"    if [ \"$REF\" != \"$HASH\" ]; then\n"
-	"        git -C \"$MIRROR_PATH\" fetch \"$REMOTE_URL\" \"$REF\"\n"
-	"    else\n"
-	"        git -C \"$MIRROR_PATH\" fetch \"$REMOTE_URL\" \"$HASH\"\n"
-	"    fi\n"
-	"    git -C \"$MIRROR_PATH\" update-ref \"ref-$HASH\" \"$HASH\"\n"
+	"    REFSPEC=\"$REF:ref-$HASH\"\n"
+	"    git -C \"$MIRROR_PATH\" fetch \"$REMOTE_URL\" \"+$REFSPEC\"\n"
 	"elif [ \"$OPERATION\" == \"checkout\" ]; then\n"
 	"    MIRROR_PATH=$1\n"
 	"    BUILD_DIR=$2\n"