remove extraneous virtual entry?

[obfusk]

This affects compare when only the second APK is v1-signed with signflinger (see FAQ; reversing the arguments should make it work), but should not ever impact copy/patch to an unsigned APK.

We could remove it when it's presumably not supposed to be there; but I currently don't think we should do that automatically.

Maybe with a --remove-virtual-entry option?

Also, split off size/presence detection into detect_zfe()?

diff --git a/apksigcopier/__init__.py b/apksigcopier/__init__.py
index 90fc5e7..6c34427 100755
--- a/apksigcopier/__init__.py
+++ b/apksigcopier/__init__.py
@@ -325,6 +325,11 @@ def copy_apk(unsigned_apk: str, output_apk: str, *, zfe_size: Optional[int] = No
             if fhi.read(zfe_size) != zfe:
                 fho.write(zfe)
             fhi.seek(0)
+        else:
+            if fhi.read(28) == zipflinger_virtual_entry(30)[:28]:
+                fhi.read(int.from_bytes(fhi.read(2), "little"))
+            else:
+                fhi.seek(0)
         for info in sorted(infos, key=lambda info: info.header_offset):
             off_i = fhi.tell()
             if info.header_offset > off_i: