autodetection of excellon drill files not reliable

Description

The automatic loading of excellon drill files in the gerber viewer sometimes works, sometimes not. It depends on the specific *.drl file.

If the special command File-->open Excellon Drill File is used the file loads correct.

Steps to reproduce

  1. download+extract the gerber-files:production.zip
  2. start gerber viewer
  3. File-->Open autodetected files
  4. select all files in the downloaded directory
  5. note:
    • gerber jobfile is rejected
    • file "pumpe_600W-NPTH.drl" is also rejected, while the corresponding drill file for plated holes is correctly recognized

KiCad Version

Application: KiCad Gerber Viewer x64 on x64

Version: 7.99.0-2677-g3cd60007c5, release build

Libraries:
	wxWidgets 3.2.2
	FreeType 2.12.1
	HarfBuzz 8.0.0
	FontConfig 2.14.2

Platform: Windows 10 (build 19045), 64-bit edition, 64 bit, Little endian, wxMSW

	wxWidgets: 3.2.2 (wchar_t,wx containers)
	Boost: 1.82.0
	OCC: 7.7.1
	Curl: 8.2.1-DEV
	ngspice: 41
	Compiler: Visual C++ 1936 without C++ ABI

Build settings: