fixtures_flake: avoid fileinput

it seems that the inplace argument in some cases picks up output from
unrelated functions. Since the file is relativly small, we can just
replace the content in one go.

pkgs/clan-cli/tests/fixtures_flakes.py

@@ -1,4 +1,3 @@
-import fileinput
 import json
 import logging
 import os
@@ -25,7 +24,9 @@ def substitute(
     flake: Path = Path(__file__).parent,
 ) -> None:
     sops_key = str(flake.joinpath("sops.key"))
-    for line in fileinput.input(file, inplace=True):
+    buf = ""
+    with file.open() as f:
+        for line in f:
             line = line.replace("__NIXPKGS__", str(nixpkgs_source()))
             if clan_core_flake:
                 line = line.replace("__CLAN_CORE__", str(clan_core_flake))
@@ -38,7 +39,8 @@ def substitute(
                 )
             line = line.replace("__CLAN_SOPS_KEY_PATH__", sops_key)
             line = line.replace("__CLAN_SOPS_KEY_DIR__", str(flake))
-        print(line, end="")
+            buf += line
+    file.write_text(buf)
 
 
 class FlakeForTest(NamedTuple):
@@ -91,10 +93,13 @@ def generate_flake(
     for file in flake.rglob("*"):
         if file.is_file():
             print(f"Final Content of {file}:")
-            for line in fileinput.input(file, inplace=True):
+            buf = ""
+            with file.open() as f:
+                for line in f:
                     for key, value in substitutions.items():
                         line = line.replace(key, value)
-                print(line, end="")
+                    buf += line
+            file.write_text(buf)
 
     # generate machines from machineConfigs
     for machine_name, machine_config in machine_configs.items():