backout: backed out changeset 67d14d4e036c

backout: backed out changeset 67d14d4e036c

Same as the previous patch, this breaks the Windows CI for some yet unknown
reason.

Differential Revision: https://phab.mercurial-scm.org/D11727

--- a/mercurial/exewrapper.c	Wed Oct 27 12:07:58 2021 +0200
+++ b/mercurial/exewrapper.c	Wed Oct 27 15:18:52 2021 +0200
@@ -29,134 +29,6 @@
 #define _countof(array) (sizeof(array) / sizeof(array[0]))
 #endif
 
-#if PY_MAJOR_VERSION >= 3
-
-#pragma comment(lib, "Advapi32.lib")
-
-/* python.org installations */
-#define CORE_PATH L"SOFTWARE\\Python\\PythonCore"
-
-/* Microsoft Store installations */
-#define LOOKASIDE_PATH                                                         \
-	L"SOFTWARE\\Microsoft\\AppModel\\Lookaside\\user\\Software\\Python\\"  \
-	L"PythonCore"
-
-static wchar_t *_locate_python_for_key(HKEY root, LPCWSTR subkey, size_t *size)
-{
-	wchar_t installPathKey[512];
-	wchar_t *executable = NULL;
-	DWORD type;
-	DWORD sz = 0;
-	HKEY ip_key;
-	LSTATUS status;
-
-	_snwprintf_s(installPathKey, sizeof(installPathKey), _TRUNCATE,
-	             L"%ls\\%d.%d\\InstallPath", subkey, PY_MAJOR_VERSION,
-	             PY_MINOR_VERSION);
-
-	status =
-	    RegOpenKeyExW(root, installPathKey, 0, KEY_QUERY_VALUE, &ip_key);
-
-	if (status != ERROR_SUCCESS)
-		return NULL;
-
-	status = RegQueryValueExW(ip_key, L"ExecutablePath", NULL, &type,
-	                          (LPBYTE)executable, &sz);
-	if (status == ERROR_SUCCESS) {
-		/* Allocate extra space so path\to\python.exe can be converted
-		 * to path\to\python39.dll + NUL.
-		 */
-		*size = sz + sizeof(_T(HGPYTHONLIB ".dll")) + sizeof(wchar_t);
-		executable = malloc(*size);
-
-		if (executable) {
-			status =
-			    RegQueryValueExW(ip_key, L"ExecutablePath", NULL,
-			                     &type, (LPBYTE)executable, &sz);
-
-			if (status != ERROR_SUCCESS) {
-				free(executable);
-				executable = NULL;
-			} else {
-				/* Not all values are stored NUL terminated */
-				executable[sz] = L'\0';
-			}
-		}
-	}
-
-	RegCloseKey(ip_key);
-	return executable;
-}
-
-static HMODULE load_system_py3(void)
-{
-	wchar_t *subkeys[] = {CORE_PATH, LOOKASIDE_PATH};
-	HKEY roots[] = {HKEY_LOCAL_MACHINE, HKEY_CURRENT_USER};
-
-	/* Give priority to python.org installs, because MS Store installs can
-	 * break with user profile corruption, and also use some NTFS feature
-	 * that MSYS doesn't understand.
-	 */
-	for (int s = 0; s < _countof(subkeys); s++) {
-		for (int r = 0; r < _countof(roots); r++) {
-			size_t size = 0;
-			wchar_t *py =
-			    _locate_python_for_key(roots[r], subkeys[s], &size);
-			wchar_t *cut = NULL;
-			HMODULE pydll;
-
-			if (!py) {
-				continue;
-			}
-
-			/* Cut off the python executable component */
-			cut = wcsrchr(py, L'\\');
-			if (cut == NULL) {
-				free(py);
-				continue;
-			}
-			*cut = 0;
-
-			wcscat_s(py, size, _T("\\" HGPYTHONLIB ".dll"));
-
-			pydll = LoadLibrary(py);
-
-			/* Also load python3.dll, so we don't pick up a random
-			 * one on PATH. We don't search {sys.prefix}\DLLs like
-			 * python.exe because this is commented as "not been a
-			 * normal install layout for a while", and don't search
-			 * LOAD_LIBRARY_SEARCH_APPLICATION_DIR because it's not
-			 * clear what the use case is.
-			 */
-			if (pydll != NULL) {
-				HANDLE py3dll = NULL;
-
-				*cut = 0;
-				wcscat_s(py, size, L"\\python3.dll");
-
-				py3dll = LoadLibrary(py);
-				if (py3dll == NULL) {
-					const char *err;
-					err = "failed to load python3.dll "
-					      "for " HGPYTHONLIB ".dll";
-					fprintf(stderr, "abort: %s (0x%X)\n",
-					        err, GetLastError());
-					exit(255);
-				}
-			}
-
-			free(py);
-
-			if (pydll != NULL) {
-				return pydll;
-			}
-		}
-	}
-
-	return NULL;
-}
-#endif
-
 static TCHAR pyscript[MAX_PATH + 10];
 static TCHAR pyhome[MAX_PATH + 10];
 static TCHAR pydllfile[MAX_PATH + 10];
@@ -236,12 +108,6 @@
 		Py_SetPythonHome(pyhome);
 	}
 
-#if PY_MAJOR_VERSION >= 3
-	if (pydll == NULL) {
-		pydll = load_system_py3();
-	}
-#endif
-
 	if (pydll == NULL) {
 		pydll = LoadLibrary(_T(HGPYTHONLIB) _T(".dll"));
 		if (pydll == NULL) {