From 5dd156c2f5a6b39cd44b865453241b22e68460d8 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 12 Feb 2023 11:45:44 -0800
Subject: [PATCH] Do not override value of an already set environment variable

---
 action.yml | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/action.yml b/action.yml
index 31ca4b0e..656c2b14 100644
--- a/action.yml
+++ b/action.yml
@@ -85,17 +85,23 @@ runs:
 
     - run: |
         : disable incremental compilation
-        echo CARGO_INCREMENTAL=0 >> $GITHUB_ENV
+        if [ -z ${CARGO_INCREMENTAL+set} ]; then
+          echo CARGO_INCREMENTAL=0 >> $GITHUB_ENV
+        fi
       shell: bash
 
     - run: |
         : enable colors in Cargo output
-        echo CARGO_TERM_COLOR=always >> $GITHUB_ENV
+        if [ -z ${CARGO_TERM_COLOR+set} ]; then
+          echo CARGO_TERM_COLOR=always >> $GITHUB_ENV
+        fi
       shell: bash
 
     - run: |
         : enable Cargo sparse registry  # ignored by stable cargo
-        echo CARGO_UNSTABLE_SPARSE_REGISTRY=true >> $GITHUB_ENV
+        if [ -z ${CARGO_UNSTABLE_SPARSE_REGISTRY+set} ]; then
+          echo CARGO_UNSTABLE_SPARSE_REGISTRY=true >> $GITHUB_ENV
+        fi
       shell: bash
 
     - run: rustc +${{steps.parse.outputs.toolchain}} --version --verbose