tests: collapse some more trivial if PYTHON3 blocks

This doesn't account for all of the references to PYTHON3. But it
accounts for the ones that are more trivial and don't entail logical
changes.

Differential Revision: https://phab.mercurial-scm.org/D12235

tests/run-tests.py

@@ -362,18 +362,10 b' def canonpath(path):'
 
 
 def which(exe):
-    if PYTHON3:
-        # shutil.which only accept bytes from 3.8
-        cmd = _bytes2sys(exe)
-        real_exec = shutil.which(cmd)
-        return _sys2bytes(real_exec)
-    else:
-        # let us do the os work
-        for p in osenvironb[b'PATH'].split(os.pathsep):
-            f = os.path.join(p, exe)
-            if os.path.isfile(f):
-                return f
-        return None
+    # shutil.which only accept bytes from 3.8
+    cmd = _bytes2sys(exe)
+    real_exec = shutil.which(cmd)
+    return _sys2bytes(real_exec)
 
 
 def parselistfiles(files, listtype, warn=True):
@@ -1864,11 +1856,8 b' class TTest(Test):'
             script.append(b'alias pwd="pwd -W"\n')
 
         if hgcatapult and hgcatapult != os.devnull:
-            if PYTHON3:
-                hgcatapult = hgcatapult.encode('utf8')
-                cataname = self.name.encode('utf8')
-            else:
-                cataname = self.name
+            hgcatapult = hgcatapult.encode('utf8')
+            cataname = self.name.encode('utf8')
 
             # Kludge: use a while loop to keep the pipe from getting
             # closed by our echo commands. The still-running file gets
@@ -2173,11 +2162,8 b' class TTest(Test):'
                     return "retry", False
 
         if el.endswith(b" (esc)\n"):
-            if PYTHON3:
-                el = el[:-7].decode('unicode_escape') + '\n'
-                el = el.encode('latin-1')
-            else:
-                el = el[:-7].decode('string-escape') + '\n'
+            el = el[:-7].decode('unicode_escape') + '\n'
+            el = el.encode('latin-1')
         if el == l or WINDOWS and el[:-1] + b'\r\n' == l:
             return True, True
         if el.endswith(b" (re)\n"):
@@ -2225,10 +2211,7 b' iolock = threading.RLock()'
 firstlock = threading.RLock()
 firsterror = False
 
-if PYTHON3:
-    base_class = unittest.TextTestResult
-else:
-    base_class = unittest._TextTestResult
+base_class = unittest.TextTestResult
 
 
 class TestResult(base_class):
@@ -2352,13 +2335,9 b' class TestResult(base_class):'
                 self.stream.write('\n')
                 for line in lines:
                     line = highlightdiff(line, self.color)
-                    if PYTHON3:
-                        self.stream.flush()
-                        self.stream.buffer.write(line)
-                        self.stream.buffer.flush()
-                    else:
-                        self.stream.write(line)
-                        self.stream.flush()
+                    self.stream.flush()
+                    self.stream.buffer.write(line)
+                    self.stream.buffer.flush()
 
                 if servefail:
                     raise test.failureException(
@@ -3247,10 +3226,7 b' class TestRunner(object):'
         fileb = _sys2bytes(__file__)
         runtestdir = os.path.abspath(os.path.dirname(fileb))
         osenvironb[b'RUNTESTDIR'] = runtestdir
-        if PYTHON3:
-            sepb = _sys2bytes(os.pathsep)
-        else:
-            sepb = os.pathsep
+        sepb = _sys2bytes(os.pathsep)
         path = [self._bindir, runtestdir] + osenvironb[b"PATH"].split(sepb)
         if os.path.islink(__file__):
             # test helper will likely be at the end of the symlink
@@ -3598,10 +3574,8 b' class TestRunner(object):'
             pyexe_names = [b'python', b'python3', b'python.exe']
         elif WINDOWS:
             pyexe_names = [b'python', b'python.exe']
-        elif PYTHON3:
+        else:
             pyexe_names = [b'python', b'python3']
-        else:
-            pyexe_names = [b'python', b'python2']
 
         # os.symlink() is a thing with py3 on Windows, but it requires
         # Administrator rights.
@@ -3766,10 +3740,7 b' class TestRunner(object):'
         else:
             with open(installerrs, 'rb') as f:
                 for line in f:
-                    if PYTHON3:
-                        sys.stdout.buffer.write(line)
-                    else:
-                        sys.stdout.write(line)
+                    sys.stdout.buffer.write(line)
             sys.exit(1)
         os.chdir(self._testdir)
 
@@ -3862,10 +3833,7 b' class TestRunner(object):'
         )
         out, _err = proc.communicate()
         if proc.returncode != 0:
-            if PYTHON3:
-                sys.stdout.buffer.write(out)
-            else:
-                sys.stdout.write(out)
+            sys.stdout.buffer.write(out)
             sys.exit(1)
 
     def _installrhg(self):
@@ -3889,10 +3857,7 b' class TestRunner(object):'
         )
         out, _err = proc.communicate()
         if proc.returncode != 0:
-            if PYTHON3:
-                sys.stdout.buffer.write(out)
-            else:
-                sys.stdout.write(out)
+            sys.stdout.buffer.write(out)
             sys.exit(1)
 
     def _build_pyoxidized(self):
@@ -3920,10 +3885,7 b' class TestRunner(object):'
         )
         out, _err = proc.communicate()
         if proc.returncode != 0:
-            if PYTHON3:
-                sys.stdout.buffer.write(out)
-            else:
-                sys.stdout.write(out)
+            sys.stdout.buffer.write(out)
             sys.exit(1)
 
     def _outputcoverage(self):