Extra blank line always added before import heading

[rafikdraoui]

When an import section that has a import_heading isn't at the module top-level, running isort on the file adds an extra new line before the heading comment every time, i.e. the transformation isn't idempotent.

config:

[settings]
known_special = special
import_heading_special = Special imports
sections=FUTURE,STDLIB,THIRDPARTY,SPECIAL,FIRSTPARTY,LOCALFOLDER

file:

from typing import TYPE_CHECKING

# Special imports
from special import thing

if TYPE_CHECKING:
    # Special imports
    from special import another_thing


def func():
    """Docstring"""

    # Special imports
    from special import something_else
    return

Running isort . gives the following diff:

diff --git a/f.py b/f.py
index f07d8ca..b71445c 100644
--- a/f.py
+++ b/f.py
@@ -4,6 +4,7 @@ from typing import TYPE_CHECKING
 from special import thing

 if TYPE_CHECKING:
+
     # Special imports
     from special import another_thing

@@ -11,6 +12,7 @@ if TYPE_CHECKING:
 def func():
     """Docstring"""

+
     # Special imports
     from special import something_else
     return

Running isort a second time modifies the file again, adding extra lines

diff --git a/f.py b/f.py
index b71445c..bc9d957 100644
--- a/f.py
+++ b/f.py
@@ -5,6 +5,7 @@ from special import thing

 if TYPE_CHECKING:

+
     # Special imports
     from special import another_thing

@@ -13,6 +14,7 @@ def func():
     """Docstring"""


+
     # Special imports
     from special import something_else
     return

And so on for further runs of isort.

[timothycrosley]

Thank you for reporting this especially nasty issue! I'm sorry it impacted you!
I've fixed it in the just released 5.0.5 patch release, with additional regression testing in place to ensure it doesn't resurface.