Allow a single ctrl-c to terminate an install in progress

lib/spack/spack/installer.py

@@ -1530,12 +1530,20 @@ def install(self, **kwargs):
                 self._update_installed(task)
                 raise
 
-            except (Exception, KeyboardInterrupt, SystemExit) as exc:
-                # Assuming best effort installs so suppress the exception and
-                # mark as a failure UNLESS this is the explicit package.
+            except KeyboardInterrupt as exc:
+                # The build has been terminated with a Ctrl-C so terminate.
                 err = 'Failed to install {0} due to {1}: {2}'
                 tty.error(err.format(pkg.name, exc.__class__.__name__,
                           str(exc)))
+                raise
+
+            except (Exception, SystemExit) as exc:
+                # Best effort installs suppress the exception and mark the
+                # package as a failure UNLESS this is the explicit package.
+                err = 'Failed to install {0} due to {1}: {2}'
+                tty.error(err.format(pkg.name, exc.__class__.__name__,
+                          str(exc)))
+
                 self._update_failed(task, True, exc)
 
                 if pkg_id == self.pkg_id:

lib/spack/spack/test/installer.py

@@ -718,6 +718,26 @@ def test_install_failed(install_mockery, monkeypatch, capsys):
     assert 'Warning: b failed to install' in out
 
 
+def test_install_fail_on_interrupt(install_mockery, monkeypatch, capsys):
+    """Test ctrl-c interrupted install."""
+    err_msg = 'mock keyboard interrupt'
+
+    def _interrupt(installer, task, **kwargs):
+        raise KeyboardInterrupt(err_msg)
+
+    spec, installer = create_installer('a')
+
+    # Raise a KeyboardInterrupt error to trigger early termination
+    monkeypatch.setattr(inst.PackageInstaller, '_install_task', _interrupt)
+
+    with pytest.raises(KeyboardInterrupt, match=err_msg):
+        installer.install()
+
+    out = str(capsys.readouterr())
+    assert 'Failed to install' in out
+    assert err_msg in out
+
+
 def test_install_lock_failures(install_mockery, monkeypatch, capfd):
     """Cover basic install lock failure handling in a single pass."""
     def _requeued(installer, task):