[Tests] nvm_ls handles hash in pattern: fix cleanup, isolate NVM_DIR, cover the sed path

- `cleanup` unset TEST_DIR before `rm -rf "${TEST_DIR-}"`, so the temp dir (with an executable fake `node`) was never removed,
and urchin executes any executable file it finds under the test dir on the next local run.
- the preexisting `foo#bar` assertions ran against the ambient NVM_DIR;
now that `#` patterns comment-strip to `foo`, a real local alias named `foo` would resolve and break them,
so all assertions now run against an isolated NVM_DIR.
- the multiline content used a full x.y.z version, which takes nvm_ls's explicit-version fast path and never reaches the find/sed pipeline where the newline actually broke sed;
a partial version exercises that path, and matching on "unterminated" covers both the BSD and GNU sed error wordings.

test/fast/Unit tests/nvm_ls handles hash in pattern

@@ -3,13 +3,22 @@
 die () { echo "$@" ; cleanup ; exit 1; }
 
 cleanup() {
-  unset NVMRC_CONTENT OUTPUT EXIT_CODE TEST_DIR
   rm -rf "${TEST_DIR-}"
+  unset NVMRC_CONTENT OUTPUT EXIT_CODE TEST_DIR NVM_DIR
 }
 
 : nvm.sh
 \. ../../../nvm.sh
 
+\. ../../common.sh
+
+# an isolated NVM_DIR with a single known version, so that ambient versions
+# and aliases can not affect any assertions
+TEST_DIR="${PWD}/nvm_ls_hash_pattern_tmp"
+mkdir -p "${TEST_DIR}/versions/node/v24.13.0/bin" || die 'failed to create test version dir'
+make_echo "${TEST_DIR}/versions/node/v24.13.0/bin/node" 'v24.13.0' || die 'failed to create test node binary'
+NVM_DIR="${TEST_DIR}"
+
 # Test: nvm_ls with pattern containing # should not cause sed error
 # This is a regression test for https://github.com/nvm-sh/nvm/issues/3761
 
@@ -28,25 +37,32 @@ echo "$OUTPUT" | grep -q "invalid command code" && \
 [ "$EXIT_CODE" = "3" ] || die "nvm_ls 'foo#bar' should exit with code 3, got $EXIT_CODE"
 echo "$OUTPUT" | grep -q "N/A" || die "nvm_ls 'foo#bar' should output N/A, got: $OUTPUT"
 
-TEST_DIR="${PWD}/nvm_ls_hash_pattern_tmp"
-mkdir -p "${TEST_DIR}/versions/node/v24.13.0/bin" || die 'failed to create test version dir'
-printf '#!/bin/sh\nprintf v24.13.0\\\\n\n' > "${TEST_DIR}/versions/node/v24.13.0/bin/node" || die 'failed to create test node binary'
-chmod +x "${TEST_DIR}/versions/node/v24.13.0/bin/node" || die 'failed to chmod test node binary'
-
-NVM_DIR="${TEST_DIR}"
 NVMRC_CONTENT='v24.13.0
 # krypton is the codename for Node.js v24.x'
 
 OUTPUT="$(nvm_ls "${NVMRC_CONTENT}" 2>&1)"
 EXIT_CODE=$?
 
-echo "$OUTPUT" | grep -q "unterminated regular expression" && \
-  die "nvm_ls with .nvmrc comments caused sed 'unterminated regular expression' error: $OUTPUT"
-
 [ "$EXIT_CODE" = "0" ] || die "nvm_ls with .nvmrc comments should exit with code 0, got $EXIT_CODE"
 [ "$OUTPUT" = "v24.13.0" ] || die "nvm_ls with .nvmrc comments should output v24.13.0, got: $OUTPUT"
 
 OUTPUT="$(nvm_version "${NVMRC_CONTENT}" 2>&1)"
 [ "$OUTPUT" = "v24.13.0" ] || die "nvm_version with .nvmrc comments should output v24.13.0, got: $OUTPUT"
 
+# a partial version reaches nvm_ls's find/sed pipeline, which is where multiline
+# patterns used to break sed ("unterminated regular expression" on BSD sed,
+# "unterminated address regex" on GNU sed); a full x.y.z version takes the
+# explicit-version fast path and never reaches it
+NVMRC_CONTENT='24
+# krypton is the codename for Node.js v24.x'
+
+OUTPUT="$(nvm_ls "${NVMRC_CONTENT}" 2>&1)"
+EXIT_CODE=$?
+
+echo "$OUTPUT" | grep -q "unterminated" && \
+  die "nvm_ls with partial version + comments caused a sed error: $OUTPUT"
+
+[ "$EXIT_CODE" = "0" ] || die "nvm_ls with partial version + comments should exit with code 0, got $EXIT_CODE"
+[ "$OUTPUT" = "v24.13.0" ] || die "nvm_ls with partial version + comments should output v24.13.0, got: $OUTPUT"
+
 cleanup