internal/rosa/python: extra script after install

This is generally for test suite, due to the lack of standard or widely agreed upon convention.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/python.go

@@ -85,6 +85,10 @@ func init() {
 type PipHelper struct {
 	// Whether to omit --no-build-isolation.
 	BuildIsolation bool
+	// Whether to enter source after install.
+	EnterSource bool
+	// Runs after install.
+	Script string
 }
 
 var _ Helper = new(PipHelper)
@@ -119,12 +123,18 @@ func (attr *PipHelper) script(name string) string {
 	--no-build-isolation \`
 	}
 
+	script := attr.Script
+	if attr.EnterSource {
+		script = "cd '/usr/src/" + name + "'\n" + script
+	}
+
 	return `
 pip3 install \
 	--no-index \
 	--prefix=/system \
 	--root=/work \` + extra + `
-	'/usr/src/` + name + `'`
+	'/usr/src/` + name + `'
+` + script
 }
 
 // newViaPip installs a pip wheel from a url.