[CI] restore test with env var BITCOIND_EXE

Author: RCasatta

.github/workflows/test.yml

@@ -20,6 +20,7 @@ jobs:
       - uses: Swatinem/rust-cache@v1.2.0
         with:
           key: ${{ matrix.feature }}${{ matrix.os }}
+        if: ${{ matrix.os != 'macos-10.15' }} # issue with hard-links on mac
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -28,11 +29,18 @@ jobs:
         with:
           command: test
           args: --features ${{ matrix.feature }}
+      - run: echo "BITCOIND_EXE=$(find ./target/debug -name bitcoind)" >> $GITHUB_ENV
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+        if: ${{ matrix.feature != '0_18_1' &&  matrix.feature != '0_18_0' && matrix.feature != '0_17_1' }} # would fail `test_multi_wallet`
+
 
   cosmetics:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
+      - uses: Swatinem/rust-cache@v1.2.0
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable