qubes: Log captured output for the second stage

Log the captured command output during the second stage, only in dev
environments. This follows what we have already done for the first
stage.

dangerzone/isolation_provider/qubes.py

@@ -24,7 +24,12 @@ from ..util import (
     get_tmp_dir,
     nonblocking_read,
 )
-from .base import MAX_CONVERSION_LOG_CHARS, IsolationProvider
+from .base import (
+    MAX_CONVERSION_LOG_CHARS,
+    PIXELS_TO_PDF_LOG_END,
+    PIXELS_TO_PDF_LOG_START,
+    IsolationProvider,
+)
 
 log = logging.getLogger(__name__)
 
@@ -167,6 +172,14 @@ class Qubes(IsolationProvider):
             asyncio.run(converter.convert(ocr_lang))
         except (RuntimeError, TimeoutError, ValueError) as e:
             raise errors.UnexpectedConversionError(str(e))
+        finally:
+            if getattr(sys, "dangerzone_dev", False):
+                out = converter.captured_output.decode()
+                text = (
+                    f"Conversion output: (pixels to PDF)\n"
+                    f"{PIXELS_TO_PDF_LOG_START}\n{out}{PIXELS_TO_PDF_LOG_END}"
+                )
+                log.info(text)
 
         shutil.move(CONVERTED_FILE_PATH, document.output_filename)
         success = True