Improve log when distutils is missing (#10713)

See https://github.com/astral-sh/uv/issues/4204 for motivation

This doesn't really reach the user experience I'd expect — i.e., we end
up saying a virtual environment "does not exist" which is a little
silly. However, I think improving the error messaging on interpreter
queries in general should be solved separately. I did one small
"general" change in
https://github.com/astral-sh/uv/pull/10713/commits/89e11d022222a999a4ba8eb73397ea314a636811
— otherwise we don't show the message at all.

---------

Co-authored-by: konsti <konstin@mailbox.org>

.github/workflows/ci.yml

@@ -680,13 +680,56 @@ jobs:
           echo "$CONDA_PREFIX"
           ./uv pip install anyio
 
+  integration-test-deadsnakes-39-linux:
+    timeout-minutes: 5
+    needs: build-binary-linux
+    name: "integration test | deadsnakes python3.9 on ubuntu"
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Install python3.9"
+        run: |
+          sudo add-apt-repository ppa:deadsnakes
+          sudo apt-get update
+          sudo apt-get install python3.9
+
+      - name: "Download binary"
+        uses: actions/download-artifact@v4
+        with:
+          name: uv-linux-${{ github.sha }}
+
+      - name: "Prepare binary"
+        run: chmod +x ./uv
+
+      - name: "Create a virtual environment"
+        run: |
+          ./uv venv -p 3.9 --python-preference only-system
+
+      - name: "Check version"
+        run: |
+          .venv/bin/python --version
+
+      - name: "Check install missing distutils"
+        run: |
+          ./uv pip install -v anyio 2>&1 | tee log.txt || true
+          # We should report that distutils is missing
+          grep 'Python installation is missing `distutils`' log.txt
+
+      - name: "Install distutils"
+        run: |
+          sudo apt-get install python3.9-distutils
+
+      - name: "Check install"
+        run: |
+          ./uv pip install -v anyio
+          # Now the install should succeed
+
   integration-test-free-threaded-linux:
     timeout-minutes: 5
     needs: build-binary-linux
     name: "integration test | free-threaded on linux"
     runs-on: ubuntu-latest
     steps:
-      - name: "install python3.13-nogil"
+      - name: "Install python3.13-nogil"
         run: |
           sudo add-apt-repository ppa:deadsnakes
           sudo apt-get update