before attribute after a timeout (#579).searchwindowsize if it was increased between calls (#579).str_last_chars rather than always 100 (#598).env parameter is specified to the spawn() orrun() family of calls containing a value for PATH, its value isPATH. This mirrors the behavior ofsubprocess.Popen in the standard library (PR #348).read_nonblocking() in classfdspawn as previously supported in version 3.3 (PR #359).