fix: remove invalid --branch flags from rust-systems Dockerfiles

The sg-evals mirrors rust--01f6ddf7 and servo--be6a2f99 only have a
main branch (orphan commit approach). The --branch <hash> flag caused
Docker build failures for tasks 044, 131, 132. Cloning default branch
(main) gets the correct pinned content.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sjarmak

benchmarks/ccb_mcp_crossorg/ccx-crossorg-132/environment/Dockerfile

@@ -14,8 +14,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 WORKDIR /workspace
 
 # Clone local checkout repos (baseline config: agent has local access to these)
-RUN git clone --depth 1 --branch 01f6ddf7 https://github.com/sg-evals/rust--01f6ddf7 /workspace/rust--01f6ddf7
-RUN git clone --depth 1 --branch be6a2f99 https://github.com/sg-evals/servo--be6a2f99 /workspace/servo--be6a2f99
+RUN git clone --depth 1 https://github.com/sg-evals/rust--01f6ddf7 /workspace/rust--01f6ddf7
+RUN git clone --depth 1 https://github.com/sg-evals/servo--be6a2f99 /workspace/servo--be6a2f99
 
 # Initialize git identity for agent commits
 RUN git config --global user.email "agent@example.com" && \

benchmarks/ccb_mcp_incident/ccx-incident-131/environment/Dockerfile

@@ -14,8 +14,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 WORKDIR /workspace
 
 # Clone local checkout repos (baseline config: agent has local access to these)
-RUN git clone --depth 1 --branch 01f6ddf7 https://github.com/sg-evals/rust--01f6ddf7 /workspace/rust--01f6ddf7
-RUN git clone --depth 1 --branch be6a2f99 https://github.com/sg-evals/servo--be6a2f99 /workspace/servo--be6a2f99
+RUN git clone --depth 1 https://github.com/sg-evals/rust--01f6ddf7 /workspace/rust--01f6ddf7
+RUN git clone --depth 1 https://github.com/sg-evals/servo--be6a2f99 /workspace/servo--be6a2f99
 
 # Initialize git identity for agent commits
 RUN git config --global user.email "agent@example.com" && \

benchmarks/ccb_mcp_onboarding/ccx-onboard-044/environment/Dockerfile

@@ -14,8 +14,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 WORKDIR /workspace
 
 # Clone local checkout repos (baseline config: agent has local access to these)
-RUN git clone --depth 1 --branch 01f6ddf7 https://github.com/sg-evals/rust--01f6ddf7 /workspace/rust--01f6ddf7
-RUN git clone --depth 1 --branch be6a2f99 https://github.com/sg-evals/servo--be6a2f99 /workspace/servo--be6a2f99
+RUN git clone --depth 1 https://github.com/sg-evals/rust--01f6ddf7 /workspace/rust--01f6ddf7
+RUN git clone --depth 1 https://github.com/sg-evals/servo--be6a2f99 /workspace/servo--be6a2f99
 
 # Initialize git identity for agent commits
 RUN git config --global user.email "agent@example.com" && \