Drop support for Tesseract 4 alpha releases without textonly_pdf (mostly)

hocr renderer can still be used

src/ocrmypdf/_validation.py

@@ -106,6 +106,14 @@ def check_options_output(options):
     if options.pdf_renderer == 'auto':
         options.pdf_renderer = 'sandwich'
 
+    if options.pdf_renderer == 'sandwich' and not tesseract.has_textonly_pdf(
+        options.tesseract_env
+    ):
+        raise MissingDependencyError(
+            "You are using an alpha version of Tesseract 4.0 that does not support "
+            "the textonly_pdf parameter. We don't support versions this old."
+        )
+
     if options.output_type == 'pdfa':
         options.output_type = 'pdfa-2'
 
@@ -216,7 +224,9 @@ def check_options_advanced(options):
             "--pdfa-image-compression argument has no effect when "
             "--output-type is not 'pdfa', 'pdfa-1', or 'pdfa-2'"
         )
-    if tesseract.v4() and (options.user_words or options.user_patterns):
+    if tesseract.v4(options.tesseract_env) and (
+        options.user_words or options.user_patterns
+    ):
         log.warning('Tesseract 4.x ignores --user-words, so this has no effect')
 
 

src/ocrmypdf/_weave.py

@@ -103,16 +103,6 @@ def _weave_layers_graft(
     pdf_text = pikepdf.open(text)
     pdf_text_contents = pdf_text.pages[0].Contents.read_bytes()
 
-    if not tesseract.has_textonly_pdf():
-        # If we don't have textonly_pdf, edit the stream to delete the
-        # instruction to draw the image Tesseract generated, which we do not
-        # use.
-        stream = bytearray(pdf_text_contents)
-        pattern = b'/Im1 Do'
-        idx = stream.find(pattern)
-        stream[idx : (idx + len(pattern))] = b' ' * len(pattern)
-        pdf_text_contents = bytes(stream)
-
     base_page = pdf_base.pages.p(page_num)
 
     # The text page always will be oriented up by this stage but the original