isolate_tests.py: Parse Sphinx block parameters correctly

test/scripts/fixtures/code_block.rst

@@ -0,0 +1,22 @@
+Some text
+
+
+.. code-block:: solidity
+
+    // SPDX-License-Identifier: GPL-3.0
+    pragma solidity >=0.7.0 <0.9.0;
+
+    contract C {
+        function foo() public view {}
+    }
+
+
+.. warning::
+
+    A Warning.
+
+::
+
+    contract C {}
+
+More text.

test/scripts/fixtures/code_block_with_directives.rst

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+A normal block with parameters.
+
+.. code-block:: solidity
+    :force:
+    :language: Solidity
+
+    // SPDX-License-Identifier: GPL-3.0
+    pragma solidity >=0.7.0 <0.9.0;
+
+    contract C {
+        function foo() public view {}
+    }
+
+
+.. warning::
+    A Warning.
+
+.. code-block:: solidity
+
+    uint constant x = 42;
+
+Text.
+
+::
+
+    contract C {}
+
+A block with blank lines between block parameters.
+Sphinx will treat the second one as a part of the code.
+
+.. code-block:: solidity
+    :force:
+
+    :language: Solidity
+
+    contract D {}
+    :linenos:
+
+Block with parameters indented less than code.
+Sphinx does not complain about these.
+
+.. code-block:: solidity
+  :force:
+  :linenos:
+
+    contract E {}
+
+More text.