Nightly hadn’t been updated since december. Now that it has been GD is missing.
Partial diff of php -i:
@@ -254,6 +251,25 @@ ftp
FTP support => enabled
FTPS support => enabled
{+gd+}
{+GD Support => enabled+}
{+GD Version => bundled (2.1.0 compatible)+}
{+FreeType Support => enabled+}
{+FreeType Linkage => with freetype+}
{+FreeType Version => 2.5.2+}
{+GIF Read Support => enabled+}
{+GIF Create Support => enabled+}
{+JPEG Support => enabled+}
{+libJPEG Version => 8+}
{+PNG Support => enabled+}
{+libPNG Version => 1.2.50+}
{+WBMP Support => enabled+}
{+XBM Support => enabled+}
{+Directive => Local Value => Master Value+}
{+gd.jpeg_ignore_warning => 1 => 1+}
gettext
GetText Support => enabled
This means that a different configure line will have to be used for PHP 7.4 and master. In this particular case it’s --enable-gd instead of --with-gd, but other changes are probably necessary as well.
Sorry for the inconvenience, just to be sure: today is it impossible to test a branch using php-nightly because of the missing --enable-gd in php configure command? I mean, until you figure out how to make php-src-builder work with 7.4, all Travis CI tests with php-nightly will fail? Is it?