tools, icu: actually failover if there are multiple URLs

Building on #23269, if multiple ICU download URLs are present, try the
next one in case of error.

Part of the ICU 63.1 bump, but independent code-wise.
#23244

PR-URL: #23715
Fixes: #22344
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

configure.py

@@ -1312,8 +1312,8 @@ def icu_download(path):
         if (md5 == gotmd5):
           return targetfile
         else:
-          error('Expected: %s      *MISMATCH*' % md5)
-          error('\n ** Corrupted ZIP? Delete %s to retry download.\n' % targetfile)
+          warn('Expected: %s      *MISMATCH*' % md5)
+          warn('\n ** Corrupted ZIP? Delete %s to retry download.\n' % targetfile)
     return None
   icu_config = {
     'variables': {}
@@ -1462,11 +1462,12 @@ def write_config(data, name):
   # ICU source dir relative to tools/icu (for .gyp file)
   o['variables']['icu_path'] = icu_full_path
   if not os.path.isdir(icu_full_path):
-    warn('* ECMA-402 (Intl) support didn\'t find ICU in %s..' % icu_full_path)
     # can we download (or find) a zipfile?
     localzip = icu_download(icu_full_path)
     if localzip:
       nodedownload.unpack(localzip, icu_parent_path)
+    else:
+      warn('* ECMA-402 (Intl) support didn\'t find ICU in %s..' % icu_full_path)
   if not os.path.isdir(icu_full_path):
     error('''Cannot build Intl without ICU in %s.
        Fix, or disable with "--with-intl=none"''' % icu_full_path)

tools/configure.d/nodedownload.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # Moved some utilities here from ../../configure
 
+from __future__ import print_function
 import urllib
 import hashlib
 import sys
@@ -36,10 +37,13 @@ def retrievefile(url, targetfile):
         sys.stdout.write(' <%s>\nConnecting...\r' % url)
         sys.stdout.flush()
         ConfigOpener().retrieve(url, targetfile, reporthook=reporthook)
-        print ''  # clear the line
+        print('')  # clear the line
         return targetfile
+    except IOError as err:
+        print(' ** IOError %s\n' % err)
+        return None
     except:
-        print ' ** Error occurred while downloading\n <%s>' % url
+        print(' ** Error occurred while downloading\n <%s>' % url)
         raise
 
 def md5sum(targetfile):
@@ -56,12 +60,12 @@ def unpack(packedfile, parent_path):
     """Unpacks packedfile into parent_path. Assumes .zip. Returns parent_path"""
     if zipfile.is_zipfile(packedfile):
         with contextlib.closing(zipfile.ZipFile(packedfile, 'r')) as icuzip:
-            print ' Extracting zipfile: %s' % packedfile
+            print(' Extracting zipfile: %s' % packedfile)
             icuzip.extractall(parent_path)
             return parent_path
     elif tarfile.is_tarfile(packedfile):
         with contextlib.closing(tarfile.TarFile.open(packedfile, 'r')) as icuzip:
-            print ' Extracting tarfile: %s' % packedfile
+            print(' Extracting tarfile: %s' % packedfile)
             icuzip.extractall(parent_path)
             return parent_path
     else:
@@ -112,7 +116,7 @@ def parse(opt):
         theRet[anOpt] = True
       else:
         # future proof: ignore unknown types
-        print 'Warning: ignoring unknown --download= type "%s"' % anOpt
+        print('Warning: ignoring unknown --download= type "%s"' % anOpt)
   # all done
   return theRet
 
@@ -122,6 +126,6 @@ def candownload(auto_downloads, package):
   if auto_downloads[package]:
     return True
   else:
-    print """Warning: Not downloading package "%s". You could pass "--download=all"
-    (Windows: "download-all") to try auto-downloading it.""" % package
+    print("""Warning: Not downloading package "%s". You could pass "--download=all"
+    (Windows: "download-all") to try auto-downloading it.""" % package)
     return False