CI: Use alternatives to select python version (#4)

* CI: Use alternatives to select python version

* CI: Specify full path to alternatives

/usr/sbin isn't in PATH

* DBG: Print uname to try to avoid bad pip install.

pip>=22 on 32-bit Cygwin seems to cause problems installing coverage.  I have no idea why this is, so I just skip upgrading pip there.

* FIX: Fix syntax of conditional for 32-bit Cygwin

I have no idea if it needs to be able to accept i386, but it will if it comes up.

* FIX: Revert earlier debug change.

.ci/install.sh

@@ -25,7 +25,7 @@ if [[ $(uname) != CYGWIN* ]]; then
                              cmake meson imagemagick libharfbuzz-dev libfribidi-dev
 fi
 
-if [[ $(uname -mo) != "i*86 Cygwin" ]]; then
+if [[ $(uname -mo) != i*86" Cygwin" ]]; then
     python3 -m pip install --upgrade pip
 fi
 

.github/workflows/test-cygwin.yml

@@ -54,9 +54,17 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-cygwin-${{ matrix.architecture }}-pip3.${{ matrix.python-minor-version }}-
             
+      - name: Ensure correct python minor version used in scripts
+        shell: bash.exe -eo pipefail -o igncr "{0}"
+        run: |
+          /usr/sbin/alternatives --set python3 /usr/bin/python3.${{ matrix.python-minor-version }}
+          /usr/sbin/alternatives --display python3
+          /usr/sbin/alternatives --set python /usr/bin/python3.${{ matrix.python-minor-version }}
+          /usr/sbin/alternatives --display python
+
       - name: Build system information
         run: |
-          dash.exe -c "python3.${{ matrix.python-minor-version }} .github/workflows/system-info.py"
+          dash.exe -c "python3 .github/workflows/system-info.py"
 
       - name: Install dependencies
         run: |
@@ -66,20 +74,20 @@ jobs:
         if: matrix.architecture == 'x86_64'
         shell: dash.exe -l "{0}"
         run: |
-          python3.${{ matrix.python-minor-version }} -m pip install -U 'numpy!=1.21.*'
+          python3 -m pip install -U 'numpy!=1.21.*'
 
       - name: Check imports
         shell: dash.exe -l "{0}"
         run: |
-          python3.${{ matrix.python-minor-version }} -c 'import numpy as np; print(np.__version__)'
+          python3 -c 'import numpy as np; print(np.__version__)'
 
       - name: Build
         shell: bash.exe -eo pipefail -o igncr "{0}"
         run: |
-          python3.${{ matrix.python-minor-version }} -m coverage erase
+          python3 -m coverage erase
           make clean
-          CFLAGS="-coverage -Werror=implicit-function-declaration" python3.${{ matrix.python-minor-version }} -m pip install -v --global-option="build_ext" .
-          python3.${{ matrix.python-minor-version }} selftest.py
+          CFLAGS="-coverage -Werror=implicit-function-declaration" python3 -m pip install -v --global-option="build_ext" .
+          python3 selftest.py
 
       - name: Rebase dlls
         shell: bash.exe -eo pipefail -o igncr "{0}"