diff --git a/doc/bugs/file_extensions_of___62__4_chars_ignored_by___42__E_backends.mdwn b/doc/bugs/file_extensions_of___62__4_chars_ignored_by___42__E_backends.mdwn
new file mode 100644
index 0000000000..5109204eab
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+++ b/doc/bugs/file_extensions_of___62__4_chars_ignored_by___42__E_backends.mdwn
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+### Please describe the problem.
+It seems that SHA256E, MD5E etc backends ignore file extensions longer than 4 characters, considering files with such extensions to have an empty extension.
+But it's not uncommon to have longer extensions; e.g. .fasta and .fasta.gz files are common in bioinformatics.
+Is it possible to remove this 4-character limit, or make it configurable?
+
+### What steps will reproduce the problem?
+(master_env_py27_v28) [12:37 PM /data/ilya-work/sw]$ cp c10.yyy c11.yyyy
+(master_env_py27_v28) [12:37 PM /data/ilya-work/sw]$ git annex calckey c11.yyyy
+SHA256E-s18841--9fd9a2607e019b7726c722d9d6f6171e6578f255bc60a0b79c525f8a3ffa05de.yyyy
+(master_env_py27_v28) [12:37 PM /data/ilya-work/sw]$ cp c10.yyy c12.yyyyy
+(master_env_py27_v28) [12:37 PM /data/ilya-work/sw]$ git annex calckey c12.yyyyy
+SHA256E-s18841--9fd9a2607e019b7726c722d9d6f6171e6578f255bc60a0b79c525f8a3ffa05de
+
+(master_env_py27_v28) [12:43 PM /data/ilya-work/sw]$ git annex calckey c10.yyyy.gz
+SHA256E-s2168--21bb6c514473754cc49a455f45bc84961fe4fceb2cb0527ba2a1cfabdce6bf80.yyyy.gz
+(master_env_py27_v28) [12:43 PM /data/ilya-work/sw]$ mv c10.yyyy.gz c10.yyyyy.gz
+(master_env_py27_v28) [12:43 PM /data/ilya-work/sw]$ git annex calckey c10.yyyyy.gz
+SHA256E-s2168--21bb6c514473754cc49a455f45bc84961fe4fceb2cb0527ba2a1cfabdce6bf80.gz
+
+### What version of git-annex are you using? On what operating system?
+
+git-annex version: 6.20180807-gebc1bb5
+build flags: Assistant Webapp Pairing S3(multipartupload)(storageclasses) WebDAV Inotify ConcurrentOutput TorrentParser MagicMime Feed\
+s Testsuite
+dependency versions: aws-0.17.1 bloomfilter-2.0.1.0 cryptonite-0.23 DAV-1.3.1 feed-0.3.12.0 ghc-8.0.2 http-client-0.5.7.0 persistent-s\
+qlite-2.6.2 torrent-10000.1.1 uuid-1.3.13 yesod-1.4.5
+key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_2\
+24 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 BLAKE2B256E BLAKE2B256 BLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE\
+2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224 BLAKE2SP256E BLAKE2SP256\
+ BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL
+remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar hook external
+operating system: linux x86_64
+supported repository versions: 3 5 6
+upgrade supported from repository versions: 0 1 2 3 4 5
+local repository version: 5
+
+
+